A fire broke out at a Moscow region cafe on Monday morning, killing three people and injuring four employees at a nearby market.

The country is on edge after a nightclub fire killed at least 146 people in Perm on Dec. 4, and fire safety inspectors have fanned out across Russia to check cafes and nightclubs on orders from Prime Minister Vladimir Putin.

Firefighters received a call about the fire at a construction materials market in Mytishchi, a town 20 kilometers northeast of Moscow, at 7:22 a.m., and they arrived 10 minutes later, Yevgeny Sekirin, chief of the Emergency Situations Ministry’s Moscow branch, told a news conference, Interfax reported.

It took firefighters about four and a half hours to douse the blaze, which covered an area of 1,500 square meters, RIA-Novosti reported. One of the injured workers suffered burns to upper respiratory passages, and the other three had bruises, the report said.

The fire created huge traffic jams at the intersection of the Moscow Ring Road and Ostashkovskoye Shosse, Interfax reported.

According to preliminary data, the fire could have been caused by overcharged electric cables, a police source told RIA-Novosti.

However, a worker at a Mytishchi market cafe told Interfax on condition of anonymity that unidentified people drove up to the cafe at about 4:30 a.m. Monday, began smashing the cafe with baseball bats and then set it on fire with gasoline.

The attack happened half an hour after a fight involving about 10 people broke out between the cafe’s staff and several customers who refused to pay their bill, the cafe worker said. Interfax didn’t say whether the attackers and the customers involved in the fight were the same people.

The Investigative Committee has opened an investigation into the incident.

•Officials have discovered fire safety violations in the official residence of Moscow’s Ded Moroz in the city’s Kuzminki district, the prefect of the southeastern administrative district said in a statement Monday.

Ded Moroz, or Grandfather Frost, will have to eliminate the violations before Dec. 20, the statement said, without elaborating on the violations.