Armed police arrive at the site of a blasting warehouse for search and rescue efforts, Aug 13, 2015. [Photo/IC]

A team of 214 military specialists in handling nuclear and biochemical materials has arrived in the northern Chinese city of Tianjin following Wednesday's warehouse explosion, thought to have been caused by volatile chemicals on site.

As of 6:30 pm, the death toll has risen to 50, including 17 firefighters. About 520 people have been admitted to hospital, among whom 66 are severely injured.

The personnel, all from the Chinese People's Liberation Army (PLA) Beijing Military Area Command, left Beijing at noon on Thursday, led by Deputy General Chief of Staff Wang Zhengrong.

The military department has also organized 130 militiamen to assist with the rescue operation, including by controlling drones and piloting helicopters to observe the site and drop water on the flames.

A total of 125 officers and soldiers on reserve duty from Tianjin Garrison Command are also working on the site.

The PLA Beijing Military Area Command sent 45 medics to set up clinics 3 km from the blast site earlier on Thursday. Seventy-eight patients have so far been treated at the clinics and transferred to other hospitals.

So far more than 1,000 firefighters, 151 fire engines and a drone have been dispatched to the blast site.