A fire in a Russian clothing factory south of Moscow killed 14 Vietnamese migrant workers Tuesday.

The blaze broke out on the second floor of the small building in the town of Yegoryevsk. A Moscow emergencies official says the doors were locked and the workers apparently tried to smash them down with hammers.

The cause of the fire is under investigation.

Asian migrants work in factories across Russia in often cramped and unsafe conditions. A fire in a market outside Moscow killed 17 workers from Tajikistan earlier this year.