Four Iranians, including two police officers, were killed and at least 11 other people injured when several buildings collapsed in the capital of Tehran, local media reported Monday.

The police officers were securing the planned demolition on Sunday of “unauthorized buildings” in the city’s southwest, ISNA news agency said that day, reporting at least three deaths in the incident.

Tasnim news agency on Monday said “four people including two policemen and two civilians died following the collapse of unauthorized buildings in the southwest of Tehran.”

Rescue operations were underway to find others who may be trapped under the rubble, ISNA and Tasnim reported.

According to ISNA, authorities had begun the demolition of one building when five others collapsed.