At least four workers were killed and three went missing as fire broke out in an air cooler manufacturing unit here on Wednesday morning, police said.

There were seven workers in the Attapur area factory during the time of the fire.

Four charred bodies were recovered and search was on for the missing men, a police official said.

The deceased, all from Bihar, were identified as Saddam, Ayub, Shahrukh and Irfan.

The cause of the fire is suspected to be a short-circuit.

The owner had locked the factory from outside, making it difficult for the workers to escape, the official said.

The police have arrested factory owner Pramod Kumar.