Mobilisation of mobs ready to run riot and prior stockpiling of projectiles by residents of affected areas took police by surprise as the scale of this week’s communal violence in the Capital became clearer in the initial investigation conducted thus far, officials in the know said on Friday.

Reports said 350 empty cartridges were recovered after over 500 rounds of gunfire during the three days of rioting in which 82 people received bullet injuries; the body count rose to 42 by Friday, with hundreds still being treated in hospitals for grievous injuries.

Heavy use of unlicensed countrymade pistols appeared to be a departure from convention when it comes to communal riots in the country, in which most victims have historically succumbed to blunt force trauma or been hacked or burnt to death, said one of the officials cited above.

“Petrol bombs, empty bottles, stones and bricks were found on the terrace and inside Hussain’s house,” a senior official of the Forensic Science Laboratory (FSL) said about AAP councillor Tahir Hussain who has been booked for murder. Investigators said such stockpiling appeared to have been a tactic deployed by scores of households in affected areas as people anticipated trouble or were willing to stir it themselves.

The resultant violence caught law-enforcement authorities off-guard, pointing to a larger intelligence failure, former officials said, to gear up for a riot in which one of the victims was, tragically, an Intelligence Bureau officer.

Prakash Singh, former director general of Uttar Pradesh police, on whose recommendations the Supreme Court issued a landmark judgment on police reforms, said, “It requires no intelligence to gauge the build-up in the area in the run-up to the riot. You will have to be blind not to act. Police could have carried all-night searches and detained all those from whose homes stones were found. The police are equally culpable of the deaths that have happened.”

Singh, who also served as director general of Assam police, said it is difficult to believe that a force of 90,000 cannot stop a riot in north-east Delhi.

“You need don’t instructions from government to act or not act. Even a sub-inspector can act on such a situation. That man Shahrukh pointing a pistol at the police officer showed the absence of the fear or respect for the law.”

The police have registered 148 cases and arrested or detained over 600 people in north-east Delhi, as the area stuttered towards normalcy while tension in some pockets still hung in the air.

Two special investigation teams (SITs), formed on Thursday to probe the national capital’s worst communal violence in at least three decades, visited the riot-ravaged areas, hunting down people who have been linked to the rampage.

Delhi Police, counting the losses, will follow the Uttar Pradesh model and make arsonists pay for the damage caused to public and private properties, two officials familiar with the move said.

Police are probing allegations that countrymade pistols were stocked by petty criminals and handed over to alleged outsiders who ran amok during the riot that started off as clashes between those supporting and protesting the Citizenship (Amendment) Act.

HT could not independently verify these reports. Special commissioner of police (law and order) SN Shrivastava said: “I have not come across any such numbers regarding the bullets fired, recovery of empty cartridges, or stocking of firearms by criminals.”

The number of those arrested or detained is likely to increase because raids are being conducted in Delhi and adjoining states, police spokesperson Mandeep Singh Randhawa said at a press briefing.

People stepped out of homes and shops were opened on Friday. Civic workers swept the streets littered with broken glasses and stones. But tension was palpable in some areas.

A 50-year-old Muslim scrap dealer was killed in the Shiv Vihar area early on Friday, his son said, though the local police did not confirm this. Even Randhawa said there was no report of fresh violence in the area.

“Some incidents of violence are being reported continuously. We have not heard of any death but residents are still in rage,” Deewan Singh, a 40-year-old resident of Shiv Vihar, said.

Friday prayers at mosques in the area — the first since the riot — passed off peacefully, local peace committee members said. Earlier in the day, mosques appealed for peace and harmony.

HT visited 10 mosques; five of them were vandalised. People who used to visit the mosques that were damaged visited neighbouring areas under police and paramilitary watch. There was heavy presence of security personnel outside empty mosques as well.

Delhi Police also initiated an “outreach programme”, and their officials met imams and maulvis of mosques. Residents alleged that on Sunday evening — hours after the first stones were thrown — at least 10 trucks carrying men with backpacks parked on a service lane in Bhajanpura.

“These people did not look like labourers. All were young men, between 20 and 30 years. Who knows what they were carrying in their backpacks? It could be stones, it could be weapons,” Om Veer, a 42-year-old shopowner, said.

At his press briefing, Randhawa said of the 148 first information reports (FIRs) filed so far, 25 cases were under the Arms Act. The others were related to murder, attempt to murder, rioting, attacking security personnel, damaging public and other offences. He said AAP councillor Tahir Hussain was still at large.

A police team visited the house of a man identified as Shahrukh. On Monday, he was caught on camera approaching a policeman while pointing a pistol at him, turning to another direction in the nick of time and then firing a few rounds in the air. He and his family members have absconded.