Tianjin, China — Huge explosions sparked overnight at a warehouse for dangerous materials in the northeastern Chinese port of Tianjin killed at least 13 people, injured hundreds and sent massive fireballs into the night sky, officials and state media outlets said Thursday.

CCTV, the state-run broadcaster, said that another 248 people had been admitted to hospitals in the city, east of Beijing. The explosions knocked off doors of buildings in the area and shattered windows up to several kilometers away.

"I thought it was an earthquake, so I rushed downstairs without my shoes on," Tianjin resident Zhang Siyu, whose home is several kilometers from the blast site, said in a telephone interview. "Only once I was outside did I realize it was an explosion. There was the huge fireball in the sky with thick clouds. Everybody could see it."

Zhang said she could see wounded people weeping. She said she did not see anyone who had been killed, but "I could feel death."

Police in Tianjin said at least seven people were killed. They said an initial blast took place late Wednesday night at shipping containers of a warehouse for hazardous materials owned by a logistics company.

The official Xinhua News agency said an initial explosion triggered other blasts at nearby businesses. The National Earthquake Bureau reported two major blasts before midnight, the first with an equivalent of 3 tons of TNT, and the second with the equivalent of 21 tons.

Photos apparently taken by bystanders and circulating on microblogs show a gigantic fireball high in the sky, with a mushroom-cloud. Other photos on state media outlets showed a sea of fire that painted the night sky bright orange, with tall plumes of smoke.

In one neighborhood of Tianjin about 6 to 12 miles from the blast site, some residents were sleeping on the street wearing gas masks, although there was no perceptible problem with the air apart from massive clouds of smoke seen in the distance.

"It was like the earthquake back in 1976 with glass breaking," resident Han Xiang said. "But then there was a huge mushroom cloud so we thought we were also in a war."

State broadcaster CCTV said six battalions of firefighters had brought the ensuing fire under control, although it was still burning. It said the firefighters were combing the neighborhood to look for further injured residents.

The logistics company was identified in state media as Ruihai Logistics. The company says on its website that it was established in 2011 and is an approved company for handling hazardous materials. It says it handles 1 million tons of cargo annually.

Tianjin is about 75 miles east of Beijing on the Bohai Sea and is one of the country's major ports.