Most of those killed were policemen and forensic team officials who were extracting samples from a large cache of explosives seized earlier this week in Haryana state, the Press Trust of India (PTI) said.
The police station suffered severe damage in the explosion and adjacent buildings were also affected, he said.
Multiple vehicles were "engulfed in flames and reduced to charred husks, with debris scattered across the site", according to a police statement.
"The intensity of the blast was such that some body parts were recovered from nearby houses, around 100-200 metres away from the police station," a source told Reuters news agency.
Most of the victims were police officers, along with forensic personnel, two crime scene photographers, and a tailor who was with the team.
Manoj Sinha, the region's Lieutenant Governor appointed by the Indian government, expressed his condolences and said he had ordered an investigation.
"I have ordered a probe to ascertain the cause of the accidental explosion. Deeply anguished by the loss of precious lives due to extremely tragic accidental blast at Nowgam police station in Srinagar. My condolences to the bereaved families. I pray for speedy recovery of the injured," he wrote on social media.
The Ministry of Home Affairs confirmed the casualties, PTI reported. The ministry’s joint secretary, Prashant Lokhande, said the cause of the incident was being investigated and any other speculation into the cause of the blast was unnecessary.
Both Lieutenant Governor Manoj Sinha and Director General of Police Nalin Prabhat termed the incident “accidental”
The governor said he has ordered a “probe to ascertain the cause of the accidental explosion”, while the police chief also stressed that “any other speculation into the cause of this incident is unnecessary”.
“Due to the sensitive and unstable nature of the recovered material, the sampling and examination were being carried out with extreme caution. Despite all precautions, an accidental blast occurred last night,” the police officer was quoted as saying by The Hindu.
“The building of the police station has been severely damaged and the adjacent buildings have been affected,” he added. “Small successive explosions” prevented immediate rescue operations by the bomb disposal squad, the PTI reported.
The local police also dismissed reports of the People’s Anti-Fascist Front (PAFF) claiming responsibility or of any other foreign link as “patently false, baseless and mischievous”.
According to the PTI, those killed in the incident included three people from the Forensic Science Laboratory, two from the revenue department, two police photographers, a member of the State Investigation Agency and a tailor.
At least 24 police personnel and three civilians were admitted to various hospitals in Srinagar, PTI quoted officials as saying.
Some of the bodies had been “completely burnt”, a police source told Reuters. “The intensity of the blast was such that some body parts were recovered from nearby houses, around 100-200 metres away from the police station.
The blast comes four days after a deadly car explosion in Delhi, which killed at least eight people in what India has called a “terror incident”.
India’s anti-terrorism National Investigation Agency is leading the probe into the blast, but so far, officials have given little further information on who the perpetrators might be — and whether it was a homegrown group or had links from abroad.
Indian media have widely connected the November 10 blast with a string of arrests just hours before, when they claimed to have seized explosive materials and assault rifles.
Indian police have carried out sweeping raids in occupied Kashmir since Wednesday. There has been no confirmation that the searches this week are connected to the New Delhi explosion, but the raids represent a renewed effort by police to tighten security after the incident.
Officers also raided Al-Falah University in Faridabad, while security forces on Friday demolished a house in occupied Kashmir’s Pulwama district.