Flammable goods at a container terminal in northern China’s Tianjin municipality exploded at about 11:30 p.m. local time on Wednesday.

At least 44 people died, including 12 firefighters, after two massive explosions ripped through a warehouse facility in one of world’s busiest ports, Chinese state media reported.

The news, reported by China’s official Xinhua News Agency and on the state television channel CCTV, comes as the city of Tianjin, located some 90 miles southeast of Beijing, struggles to come to terms with the industrial accident, which also injured as many as 400 people.

Some 32 people were reported to be hospitalized in critical condition Thursday morning, as residents posted photos of blown out windows and doors on social media.

The first blast which occurred around 11:30 p.m. local time Wednesday night was equivalent to that caused by 3 tons of TNT. The second explosion, triggered by the fire caused by the first, had the power of blast created by 21 tons of the explosive material, the National Earthquake Bureau said.

Executives for Ruihai Logistics, the company which owns the warehouse where the inferno originated, have been arrested local police said.

The website for Ruihai Logistics said the company is approved to handle hazardous materials.

China’s President Xi Jinping also demanded severe punishment for anyone found responsible for the blast.

State broadcaster CCTV said six battalions of firefighters had brought the ensuing fire under control, although it was still burning in the early hours of Thursday and authorities announced they had suspended further efforts to douse the blaze because they had not been given clear information as to the nature of the potentially hazardous materials being stored in the warehouses.

Buildings of a half-dozen companies were destroyed in the blasts, and more than 1,000 new cars were left charred in a nearby parking lot, the Beijing News said.

Accidents of this nature are not uncommon in China’s rapidly expanding cities, where residential areas bump up against industrial zones.

Tianjin is currently being incorporated into the Chinese capital of Beijing, as part of a plan to create a super city of over 130 million people known as Jing-Jin-Ji.

A spokesman for Tianjin’s port said it was operating normally, despite the fire.