Explosions in the Chinese city of Tianjin have left at least 50 people dead, including 12 firefighters, and 700 others hospitalized, Chinese authorities report.

The blasts, which occurred at the Tianjin Binhai New Development Zone around 15:30 GMT Wednesday evening, left several nearby tower blocks without power and was allegedly large enough to register on earthquake sensors, according to The Wall Street Journal. The explosions also ripped through buildings, burned out thousands of nearby cars and shattered windows in over a mile radius.

The warehouse, owned by Tianjin Dongjiang Port Rui Hai International Logistics Co., was used to handle and store volatile chemicals, CNN reported. Military personnel specializing in handling such materials assessed the scene and found that some chemical pollutants near the blast site were above regulatory thresholds.

The video below shows the initial blast:

About 400 people reportedly checked into a local hospital shortly after the explosion. However, as the evening progressed, the Tianjin government's information office confirmed that the amount of people hospitalized rose to 700, with 71 critically injured. One medic at the scene noted that many of the victims were initially brought by ambulances, but others were later forced to arrive on their own after hospitals became inundated with calls.

An employee of another hospital reported that the emergency department reached capacity, and staff had little choice but to call all their doctors to accommodate the influx of patients, as previously reported by HNGN

"The hospital cannot count how many patients we have received - there are too many of them and many of them have burn injuries," said one doctor at another hospital, who had been called back from a conference in Beijing to treat the injured, Chinese newspaper The Beijing News reported.

Relatives stood outside one local hospital throughout the night and well into the morning, waiting for news of their loved ones.

Take a look at the aftermath of Tianjin explosions below:

Authorities placed several company executives in custody following the explosions, but they have made no progress into figuring out what exactly caused the blasts.