Chinese officials work to determine cause of explosions that killed more than 50

Chinese officials on Friday defended firefighters after experts said their use of water to fight a fire may have contributed to the massive explosions that killed more than 50 people and injured hundreds in Tianjin on Wednesday.

The blast happened in Tianjin Binhai New Development Zone at 11:30 p.m. local time when a local storehouse containing explosive material blew up. More than 700 people were hospitalized after the explosions, 25 with critical injuries and 33 in serious condition.

The cause for the explosion is not clear. Reuters reported that the container was on fire shortly before the explosions, and the first firefighters at the scene used water. That water could have combined with calcium carbide, a carbon that was present in the containers and would have reacted with water, creating the explosive gas acetylene.

However, it is not known when the firefighters used the water or if it was a direct cause of the explosions.

People’s Daily, a Chinese news outlet, tweeted photos of the explosions shortly after they occurred.

#Breaking: Explosion happened in E China’s Tianjin City Wed. Huge mushroom cloud seen. Quake felt 10 km away. pic.twitter.com/PkgzFb8kyv

— People’s Daily,China (@PDChina) August 12, 2015

Chinese news agency Xinhua described the blast according to local residents:

Residents in neighborhoods nearby said flame lit up the sky and the blast with a big noise blew up dust of dozens of meters high. The explosion also shattered their window glass and fish tanks.

At least 21 firefighters died in the incident, which Reuters reported was “possibly the highest death toll among fire crews” since the People’s Republic of China was founded in 1949.

Tianjin is an industrial port city to the southeast of Beijing and has a population of approximately 15.2 million.

This post will be updated.