JOHANNESBURG, South Africa (AP) _ An explosion likely caused by an illegally placed barrel of chemicals killed 11 workers in a factory near Johannesburg, a police spokesman said Saturday.

The explosion occurred between 10 p.m. and 11 p.m. Friday, police spokesman Superintendent Richard Luvhengo said. A barrel of chemicals that should have been stored outside likely started a fire that caused gas bottles to explode, he said.

The factory, which manufactures floor polish, was required to have an additional escape route because it used flammable chemicals, but it appeared there was none, Luvhengo said. It appeared the victims ran in different directions inside the factory, trying to find a way out, he said. One suffocated, while the rest were burned beyond recognition.

Police were investigating whether the dead workers had been locked into the factory, Luvhengo said.