TIANJIN, Aug. 13 -- Two firefighters were "out of contact" and another four injured as of 3:00 a.m. Thursday after an explosion ripped through a warehouse in north China's Tianjin City, according to police authority.

According to the Sina Weibo post of the firefighting bureau under the Ministry of Public Security, The Tianjin firebrigade sent 12 teams after receiving fire report from Ruihai warehouse at the Binhai New Area at 10:50 p.m. Wednesday, which stores dangerous and chemical goods. An explosion occurred at the site at 11:30 p.m. The brigade then sent another nine teams and 35 fire engines as reinforecement.

The shockwaves were felt kilometers away, with some residents claiming their window glass and fish tanks shattered. People in neighborhoods nearby said flames lit up the sky and the blasts with big bang sent smoke and dust dozens of meters into the sky.

Lu Yun, head of the nearby Taida Hospital, said they have received more than 50 wounded people, and more are coming. The injuries were mainly from broken glass or stones. Some of the injuries are serious.

The rescue operation is still going on.