Officials say an incomplete building collapsed in southwestern Iran, killing at least four people and trapping nearly 80 others.

“Parts of the 10-story Metropol building, located in Abadan, capital of Khuzestan province, collapsed,” state television said, noting that the premises was still under construction.

An initial toll confirmed that at least “four people have lost their lives and 21 others have been injured,” Mojtaba Khaledi, spokesman for the national rescue service, was quoted as saying.

At least 80 people were trapped under the rubble and rescue dogs were deployed to help locate them, according to a regional branch of the Red Crescent.

According to state media, the building is on Abadan’s busiest street, where “commercial, medical, and office” facilities prevail.

The cause of the collapse was being researched.