At least four people were killed and 26 others injured in a suspected gas explosion in the food court of a Taiwan shopping mall on Thursday morning, according to Taiwan’s state-owned news outlet.

The explosion occurred in the city of Taichung, about 100 miles southwest of Taipei, Taiwan’s capital, local officials said. The fire department received a report at 11:33 a.m. about a possible gas explosion on the 12th floor of the mall and dispatched 136 personnel, the department said in a statement. Search and rescue teams stayed on site until about 5 p.m., the news outlet, the Central News Agency, reported.

It is unclear what caused the blast, the fire department said. Video shared online by the Taiwanese station TVBS News shows an explosion in the middle floors of the building that sent debris and dust into the street.

President Lai Ching-te of Taiwan, writing on his Facebook page, called for a prompt investigation into the cause of the accident. He said that the health ministry was coordinating medical resources to provide care to the injured.

Claire Fu contributed reporting from Seoul, and Amy Chang Chien from Taipei.