Huge fire breaks out at steel plant next to Tokyo's Haneda airport

A huge blaze at a steel plant next to Tokyo's Haneda International Airport led to arriving flights being diverted briefly to an alternative landing strip.

The fire broke out at the facility owned by Nippon Steel in Kawasaki City Monday morning, Kota Tanabe, a spokesman with Kawasaki City Fire department told CNN.

Tanabe said 16 fire engines and a helicopter were deployed to the scene.

Video shared with CNN from traveler Darren Pauls showed planes still moving on the tarmac as plumes of thick, black smoke rose above the airport.

Takameru 

Pauls said that the building is still smoldering and that there are at least four helicopters over the site.

There are no immediate report of casualties, but the situation is still not all clear, Tanabe said. The cause is still unknown and will be investigated once the fire and smoke is contained.

Services at the airport have returned to normal, said Takashi Kudo of the Ministry of Land and Transportation.

Second blaze

The plant blaze came hours after an explosion set a storage building alight at a U.S. military base in Sagamihara City in north-central Kanagawa Prefecture, which borders the capital.

There were no reported injuries, while the cause is under investigation, Tiffany Carter, a spokeswoman for the U.S. Marine Corps in Japan told CNN in an email Monday.

"The storage building is not designated as a hazardous material storage facility as some initial reports indicated. Inside the building that exploded were canisters of compressed gasses: Nitrogen, Oxygen, Freon, and air. The Sagami General Depot does not store ammunition or radiological materials," she said.