Tension prevailed in Jharkhand capital Ranchi on Sunday, as police strengthened security in sensitive areas and registered 25 FIRs against "thousands" of people in the aftermath of violent protests over controversial comments on Prophet Mohammad.

Internet services, however, were restored in the district after nearly 33 hours, Ranchi Deputy Commissioner Chhavi Ranjan said.

Around 3,500 security personnel are on guard at sensitive areas in Ranchi, where two people were killed and more than two dozen people critically injured, as protests and clashes rocked the city after the Friday prayers.

The protesters have been demanding the arrest of suspended BJP spokesperson Nupur Sharma and expelled leader Naveen Jindal for their controversial remarks on Prophet Mohammad.

Ranchi Senior Superintendent of Police Surendra Kumar Jha said personnel of the Rapid Action Force, anti-terrorism squad, special task force and district police have been deputed at strategic locations, including 38 identified vulnerable pockets .

Fifty motorcycle patrol teams have also been pressed into service.

"Twenty-five FIRs have been registered against 22 named people, and thousands of unnamed people. No arrests have been made so far. Interrogation is underway based on inputs from intelligence, CID and social media," Jha said at a press conference here.

In reply to queries regarding police firing, he said there are certain standard operating procedures to deal with such situations, which were adhered to.

"Firing is the last resort. We followed all norms before resorting to firing, as the crowd was aggressive and uncontrollable. I don't want to talk much on this as the matter is under investigation," Jha said.

Ranjan said prohibitory orders under Section 144 have been lifted from six of the 12 police station areas.

Restrictions on movement of five or more persons continue in Kotwali, Lower Bazar, Chutia, Daily Market, Doranda and Hindipiri stations, but people have been allowed to purchase daily essentials while adhering to the provisions, he said.

Security in other parts of Jharkhand has also been beefed up, as per reports from districts.

Md Haji Hasim, the president of Daily Market Traders Association, told PTI that nearly 1,100 shops are shut.

Meanwhile, internet services in Ranchi district, which were suspended from 7 pm on Friday as a precautionary measure, resumed after 33 hours.

The internet services were restored at 4 am on Sunday, Ranjan said.

Police had on Saturday said 12 of its personnel and an equal number of civilians were injured in the protests that turned violent.

Eyewitnesses, however, have claimed the number could be over 60.

A RIMS official told PTI that eight injured people undergoing treatment at the medical facility are critical, with one Nadeem Ansari, 24, still on a ventilator and battling for life.