Arizona train derailment ignites massive fire and partial bridge collapse

No injuries reported as police close Tempe Town Lake over safety fears

A train derailment in Arizona sparked a fireball that left up to 10 carriages burning and caused the partial collapse of a bridge over Tempe Town Lake.

Video from the scene showed acrid black smoke billowing over the lake as emergency crews attempted to control flames moving towards cars marked "hazardous materials".

The accident, just east of Phoenix, happened about 6.30 am local time on Wednesday morning. Tempe police warned people to avoid the area while Tempe Fire Medical Rescue reported that the second alarm fire was burning through multiple cars carrying lumber.

Tempe Police chief Sylvia Moir said no injuries were reported but that the scene is very dangerous.

"For safety measures, all of Tempe Town Lake is closed until further notice," Tempe Police said.

Authorities are working to determine the cause of the derailment, which left a portion of the Salt River Union Pacific Bridge collapsed.

Planes from a nearby airport were being diverted from the smoke while more than 90 firefighters were on scene.

Valley Metro announced that light rail was being rerouted while busses would carry passengers around the crash site, just west of downtown Tempe.

City officials said all lake activities were cancelled.

Cyclist Camille Kimball told 3TV that she rode her bike below the bridge just before it's collapse.

"Now there's fire pouring into the lake from the middle of the bridge," Ms Kimball said. "It looks like a scene from hell, truly. ... The flames are intense and the sky is filled with black smoke."

Union Pacific said as many as 10 of the freight train's cars derailed on the south side of the bridge before it collapsed and caught fire. Crew was not hurt but one person at the park was treated for smoke inhalation.

Union Pacific spokesman Tim McMahan said two of the three tanker cars on the ground under the bridge contained cyclohexanone while the third contained a rubber material. "None are reported leaking, and no tank cars were involved in the fire," he said, per AZfamily.