A major fire at a restaurant in Delhi’s Malviya Nagar area has left 21 people dead, officials said on Tuesday. Several others suffered injuries and were rushed to hospital.

The blaze reportedly broke out in the basement of the building. After receiving information, fire and police teams reached the spot and multiple fire engines were pressed into service.

Authorities fear more people may have been trapped inside, and rescue operations are being carried out at full scale. Officials said 11 people have been rescued so far.

Hospitals are providing intensive care to 37 injured persons. The cause of the fire is not yet known.

Delhi Police said an investigation is under way and efforts are on to identify the bodies. Most of the deceased are believed to be foreign nationals, according to initial information.