Copious rain lashed large swathes of northeastern India, including Assam, Meghalaya, Tripura, Nagaland and Arunachal Pradesh, worsening the flood situation in several places, even as the Met department forecast more downpour in the region over the next five days.

Two children were crushed to death when a landslide led to a house collapse in Azad Nagar area of Goalpara district in Assam on Thursday, and two persons drowned in floodwater in Dima Hasao and Udalguri, raising the toll due to floods and mudslides in the state this year to 46, officials said.

Extremely heavy rain was recorded at isolated places in Meghalaya, Assam, sub-Himalayan West Bengal and Sikkim, and heavy to very heavy downpour in Nagaland and Tripura, an official of the Met department said.

The weatherman has forecast widespread thundershowers with isolated heavy to very heavy rainfall over all the northeastern states, adjoining sub-Himalayan West Bengal and Sikkim during the next five days.

The southwest monsoon is likely to advance further in another two to three days into the remaining areas of sub-Himalayan West Bengal, some parts of Gangetic Bengal, Bihar, Jharkhand and Odisha, the Met office said.

Sohra in Meghalaya recorded the highest rainfall in 24 hours till 8.30 am of Thursday at 70 cm, followed by Kokrajhar (32 cm), Gosaingaon (32 cm), Goalpara (23 cm) and Nalbari (23 cm) in Assam, Jalpaiguri (23 cm), Hasimara (22 cm) and Alipurduar (21 cm) in sub-Himalayan West Bengal, Bhalukpong (10 cm) in Arunachal Pradesh, the Met department said.

The downpour caused injuries to three persons in Noonmati area of Guwahati, as multiple landslides were reported across the city during the day.

In several areas, including Joypur in Kharguli area, Bonda Colony, South Sarania, Amayapur in Geetanagar and 12 Mile, piles of debris led to road blockades.

At least 18 districts in Assam are experiencing heavy rain, with the inundation of fresh areas reported from Kamrup, Nalbari and Barpeta districts, the officials said.

Nearly 75,000 people have been affected by floods in those districts, they said.

The water level in river Brahmaputra and its tributaries are on the rise, while river Manas was flowing above the danger mark in some places, the officials added.

Normal life in Assam's largest city Guwahati has been severely affected due to waterlogging in most parts for the third consecutive day with areas such as Anil Nagar, Nabin Nagae, Zoo Road, Six Mile, Noonmati, Bhootnath, Maligaon figuring among the worst-hit.

District authorities have opened seven camps and nine relief distribution centres for assisting people under distress.

According to a bulletin issued by the Assam State Disaster Management Authority (ASDMA), 13 embankments were breached, and 64 roads and a bridge were damaged due to the deluge.

Meanwhile, the surface link between Tripura and the rest of the country snapped on Thursday following massive landslides triggered by heavy rainfall on National Highway-6, the officials said.

Train services in Tripura have been disrupted for the past one month due to torrential rain.