A fire broke out at a shoe factory in Delhi’s Udyog Nagar on Monday, ANI reported. Six factory workers are feared missing.

Atul Garg, the chief of Delhi Fire Services, said that the department received a call about the blaze at 8.22 am, and 31 fire tenders were sent to the spot. He added that firefighting operations could go on till late evening, according to the Hindustan Times. More than 50 firefighters are at the scene.

“As far as casualties are concerned, we have not found any bodies,” Garg added. “The factory owner is saying that six workers are missing. They may be trapped inside but we cannot confirm or deny it at this moment.”

Two Centralised Accident and Trauma Services ambulances were also sent to the factory, Parvinder Singh, deputy commissioner of police (outer district), told The Indian Express.

Unidentified officials said that the building did not have adequate fire safety arrangements. “The building had only one staircase and not enough facilities for ventilation,” an official told the newspaper. “The exact cause of the blaze is not yet known but electrical short-circuit is suspected to be one of the reasons behind the incident.”