A team of 217 military specialists in nuclear and biochemical materials has arrived in the northern city of Tianjin following explosions at a warehouse on Wednesday.

The People's Liberation Army (PLA) Beijing Military Area Command team, led by Dep. Gen. Chief of Staff Wang Zhengrong, left Beijing at noon on Thursday.

The military team first tested the air around the site for toxic gases.

"According to our preliminary detection efforts, we suggested that rescue teams move upwind," Du Jiang, political commissar of the team.

There is thick smoke in the area and there are concerns that it may contain poisonous substance. Rescue teams that are working near the center of the blast site have been ordered to wear heavy protective suits.

Standing about 1 km away from the site, a pungent smell is heavy in the air and people have complained of stinging eyes.

According to the National Health and Family Planning Commission, 36 clinical and psychological specialists from 10 civil and military hospitals in Beijing have been despatched.

The commission also called for more blood, medical instruments and drugs, and for the swift transfer of the injured.

Binhai New Area military department has also organized 130 personnel to assist the operation, including those that will control drones, and pilot helicopters to observe the site and douse the flames with water.

A total of 125 officers and soldiers on reserve duty from Tianjin Garrison Command are also on 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 and transferred to other hospitals.

So far, the death toll has climbed to 50 with 701 admitted to hospital.

The first explosion occurred around 11:30 p.m. on Wednesday at the warehouse in the Binhai New Area. Only seconds later, a second blast wreaked more havoc, shooting fireballs into the sky, damaging nearby buildings and setting cars on fire.