As many as 95 people are still missing after last week's attack near Moscow when gunmen sprayed concertgoers with automatic weapons and set the venue on fire, a Russian news outlet reported on Wednesday.

The official toll from the attack on Crocus City Hall now stands at 140 dead and 182 wounded. But the Baza news service, which has good contacts in Russian security and law enforcement, said 95 more people appeared in lists compiled by the emergency services based on appeals from people about missing relatives.

"These lists include people with whom relatives have not been able to get in touch since the terrorist attack, but who are not on the lists of wounded and dead," Baza said. "Some of these people died, but have not yet been identified."

Russian investigators said the attack was carried out by four shooters using Kalashnikov automatic weapons. More than 500 rounds were found at the scene.

The shooting began shortly before the Soviet-era rock group "Picnic" was set to play to a full house of 6,200 people. More than 200 people could have been in the blazing building moments before the roof collapsed, Baza reported on Saturday, citing emergency service sources who reviewed surveillance footage.

Russian social media channels have been flooded in the days since the shooting with appeals to help find victims.

Gathering in a Telegram chat called "Crocus. Help Centre," friends and relatives shared names of missing concertgoers and offered support.