OMAHA, Neb. (WOWT) -- Fire officials are investigating the cause of a three-alarm fire in Omaha. 

Omaha firefighters gave our partners at WOWT Channel 6 an update early Thursday about a three-alarm fire at a recycling business.

The call came out at First Star Recycling at 10:24 p.m. Wednesday. Eventually, about 70 firefighters were at the scene at 103rd & I Street.

A second alarm was declared at 10:44 p.m. and a third alarm came in at 11:03 p.m.

A Mayday alert was heard around 11:44 p.m. after a fire captain became separated from a hose line. The fire captain was found after four minutes.

He was evaluated by medics and was doing well.

Fire investigators have not determined a cause of the fire. At a 7 a.m. briefing, they said it was unknown if anyone was inside the facility at the time or exactly where the fire started.

The fire was still not considered under control at 7 a.m. because small areas were burning in areas that firefighters could not gain access due to compacted paper.

There were no concerns about air quality. Paper products provided most of the fuel for the fire.

First Star Recycling provides residential recycling services including Omaha. Just this week, 6 News was at the facility which had just begun producing plastic lumber and other products from Omaha’s orange bag recycling program.