Dhaka, Bangladesh: At least 19 are killed and dozens injured in a building explosion

(CNN) An explosion rocked a building in a crowded area of ​​the Bangladeshi capital on Tuesday, killing at least 19 people and injuring more than 50 others, according to authorities in the South Asian country.

Mahaduddin Khondikar, Additional Commissioner of Dhaka Metropolitan Police, said the cause of the blast was unknown but it may have been a gas explosion.

“We are not sure, but it seems to be accidental,” he said, adding that the number of casualties and the extent of damage will become clear after firefighters and rescue workers complete their operations.

Dhaka Metropolitan Police said many people were not inside the building at the time of the blast, but its location on a busy road near a market led to pedestrians being affected.

The photos show firefighters and emergency responders conducting search and rescue operations after dark. The walls of the destroyed building are collapsed and missing. Some units appear to have collapsed completely and debris covers the ground outside. Relatives of the victims were seen mourning outside.

As of Wednesday morning, 22 people remain hospitalized, according to Fire Chief Denomony Sharma.

Sharma said the Bangladeshi army would work to secure the rest of the building on Wednesday and an investigation would be conducted into the cause of the blast.

The blast follows two other deadly blasts last weekend in the country. Three people were killed on Sunday in a suspected gas explosion in Dhaka, a densely populated metropolis of more than 23 million people.

Seven people were killed and several others injured Saturday when a fire broke out following an explosion at an oxygen plant in southeastern Bangladesh.

Additional reporting from Reuters.