A massive fire has erupted at a steel pipe plant near a key airport in the Japanese capital of Tokyo, hours after a huge blast rocked a warehouse at a US military installation near the capital, causing a massive blaze.

Local television networks on Monday broadcast images showing plumes of dense black smoke and flames stretching up into the air.

Tokyo’s law enforcement and fire department authorities refused to speculate on whether the fire at the airport and the blast at the US base were somehow connected.

“We do not know any details at this point,” said a police spokesman in response to a question on any links between the two incidents.

Earlier in the day, an explosion ripped through the US military facility reportedly used for the storage of fuel and munitions, sending sparks into the sky and causing a massive fire that burned through the night. There were no reports of injuries, however.

The steel plant near Tokyo’s busy Haneda International Airport is owned by a unit of steelmaker giant Nippon Steel & Sumitomo Metal, which refused to comment on the incident following the large blaze.

The massive steel pipe-making facility, which spans 20,800 square meters, operates a pair of manufacturing lines, nearly a kilometer from the airport.

However, a local fire department official said, “A fire broke out from a two-meter cooling tower,” without elaborating.

The blaze reportedly spread to a next door cosmetics factory owned by Japan’s Kao. Local broadcaster NHK said nearly 600 of its employees were evacuated from the facility.

There have been no immediate reports potential casualties at the Nippon Steel factory.

Last year, at least 15 people were wounded after a blast rocked a Nippon Steel plant in central Japan.