Crews fought a relatively small but spectacular fire at the new Mosaic Stadium site in Regina on Wednesday morning.

At around 8 a.m. CST, flames and billowing thick black smoke could be seen coming from the site, close to where the $278 million stadium is being constructed.

Fire broke out around 8 a.m. CST at the site of Regina's under-construction football stadium. (Chris Lane/CBC)

By 8:20, the fire was under control, after two pumper trucks had been called in. A third truck was on standby.

Fire officials said precautions had been taken at the site so that combustible materials were separated, so any fire couldn't easily spread.

Wood and other materials were seen close to the blaze, but it was not immediately clear what had caused the thick black smoke.

Twitter users reported that downtown Regina, downwind of the fire, smelled of burned rubber and plastic.

No one was hurt. The cause is under investigation.

The stadium, a replacement for the city's existing Mosaic Stadium, is about 22 per cent completed. It's supposed to be substantially completed by August 2016, with the first Riders game set for August 2017.