Meghalaya Chief Minister Conrad Sangma on Thursday said Union Home Minister Amit Shah has given firm assurances at a meeting held in Delhi of acting on his request for a CBI probe into the "firing by Assam Police" along the states' border.

However, even as the meeting unfolded in the national capital, mob anger over alleged shooting of tribal villagers from the state by Assam police spilled over on to the streets of the picturesque hill resort of Shillong. A police bus and a jeep were torched as stones and petrol bombs flew thick and fast.

Seven people, including four police personnel, were injured in the clash that broke out between the angry protesters and the police, Superintendent of Police (City) Vivek Syiem told PTI.

Protestors were demonstrating against the shooting of five tribal villagers by Assam police in the early hours of Tuesday at Mukroh, in West Jaintia Hills on the disputed Assam-Meghalaya border.The home ministry spokesperson later tweeted that Shah has assured a CBI probe -- a demand also raised by the Assam government -- into the firing incident.

"Meghalaya CM @SangmaConrad met Union Home & Co-op Minister @AmitShah today and requested CBI enquiry into unfortunate incident on Assam-Meghalaya border. Govt of Assam has also requested CBI enquiry into the matter. HM @AmitShah has assured that GOI will conduct CBI enquiry," the tweet said.Sangma who was accompanied by his Cabinet colleagues in his meeting with Shah, also highlighted problems in the supply of essential commodities such as auto-fuel, and said he requested the support of the Centre and other states to ensure that there was no disruptions.

Violence had broken out at the border between the two states in the early hours of Tuesday after a truck allegedly laden with illegally felled timber was intercepted by forest guards from Assam. Six people, including five tribal villagers from Meghalaya a forest guard from Assam, were killed.

On Thursday, Shillong's street protests took on a violent turn as petrol bombs were hurled at a police bus and jeep, setting them on fire, while a traffic police kiosk was brought down. Stones and petrol bombs were hurled at police at Barik point, barely metres from the place where a candlelight vigil and sit-in protest was held by different organisations, including the Khasi Students Union, and the Federation of Khasi Jaintia and Garo People, officials said.

Police said they had to use tear gas shells to bring the situation under control.Those behind the violence were yet to be identified, police said.Shops and business establishments run by non-tribals in Khyndailad, Iewduh and other areas in Shillong were closed early, apprehending violence.

Security in areas, identified as vulnerable, in the city was tightened, a senior district official told PTI.The situation is tense but under control with leaders of different organisations appealing for peace, he said.

Different organisations in Meghalaya have announced a "non-cooperation movement" on Friday across the five hill districts.

Mobile internet services were suspended in these districts till Saturday morning to prevent the spread of fake news that could foment trouble, Home Secretary CVD Diengdoh said.

The Meghalaya government was arranging police protection for trucks transporting essential commodities and oil tankers that were coming from Assam, officials said on Thursday night.

In a letter to the deputy collectors of at least seven districts, Food and Civil Supplies director Pravin Bakshi directed for the arrangement of police escorts to such vehicles after the Assam Petroleum Mazdoor Union (APMU) announced that it has stopped transporting fuel to Meghalaya fearing violence."Necessary arrangements for patrolling/providing police escorts wherever possible may kindly be explored on all national highways to ensure smooth movement of vehicles carrying essential commodities," the letter stated.

Serpentine queues of vehicles were also seen at petrol pumps across Meghalaya on Thursday evening after the apex body of petroleum workers in Assam said it has stopped transportation of fuel to the neighbouring state.

Hundreds of vehicles were seen waiting at the petrol pumps as people scrambled to fill up tanks fearing shortage. The queues of vehicles led to traffic snarls in Shillong and some other parts of the state.Police officers were seen regulating the movement of vehicles at some petrol pumps where motorists turned unruly while waiting for their turn.

The Assam Petroleum Mazdoor Union (APMU) sent letters to all PSU oil marketing companies, including IOC, HPCL and BPCL, informing them about its decision to not load fuel in tankers meant for Meghalaya.The union expressed concern over the safety of Assam vehicles in Meghalaya amid violence following the killing of six people at the inter-state border.

"Our drivers and handymen were attacked when there were disturbances in Meghalaya earlier. Some of them were critically injured. They have become handicapped for their whole lives. We cannot take any risk again," APMU general secretary Ramen Das told PTI.

He alleged that trucks supplying non-petroleum products were pelted with stones in the last two days but "no harm has been done to oil tankers as of now".

"Therefore, we have decided not to take any load from today onwards until and unless Government of Meghalaya assures us (of) the safety and security of T/T (tank trucks) crews," the letter said.

Earlier the presence of heavy police reinforcements ensured the situation along the Assam-Meghalaya border, remained tense but peaceful, a senior official said on Thursday.

Restrictions under Section 144 of the CrPC have also been imposed at the clash site and surrounding areas, she said.

"The situation is peaceful and a strong presence of security personnel have been ensured till the atmosphere normalises completely. Our magistrates are visiting the place daily," the official told PTI.

Meanwhile, the Meghalaya government extended suspension of mobile internet services in at least seven Khasi-Jaintia Hills districts in the eastern part of the state till Saturday, officials said.

"To prevent misuse of social media to disturb peace and tranquillity, and to maintain law and order, mobile internet and data services stand withdrawn for a period of 48 hours," Home Department Secretary CVD Diengdoh told PTI.

Mobile internet services were suspended in the seven districts on Tuesday, hours after the violence erupted.

The Assam government on Wednesday handed over the body of the forest guard to his family members after post-mortem, the officials said.

Assam and Meghalaya have a long-standing dispute in 12 areas along the 884.9-km-long inter-state border, and the location where the violence took place is one of those.

The two states had signed a memorandum of understanding in March this year towards ending the dispute in six of the areas.

Meghalaya was carved out of Assam in 1972 and had since then challenged the Assam Reorganisation Act, 1971, which demarcated the border between the two states.