At least four people are dead following a suspected Thursday morning gas explosion at Taiwan's Shin Kong Mitsukoshi department store.

Video of the blast shows glass and debris violently ejecting from the building ... on what otherwise looked like a routine morning in Taichung City. The explosion left a mess of litter all over the ground, and a gaping hole in the structure.

AP reports the explosion occurred at approximately 11:30 AM local time in the 12th-floor food court, though multiple floors were destroyed.

At least 26 others were reportedly injured, while 235 were evacuated from the building.

Taichung Vice Mayor Cheng Chao-hsin reportedly told the press renovations had been underway at the mall prior to the explosion ... and an investigation is in progress.

He said ... "If it’s found there were illegal actions or parts that violated renovation regulations, it will be dealt with appropriately."