A thunderstorm that passed through the Casper area ignited three grass fires Wednesday afternoon.

Two fires are contained an in the mop-up stage and crews are currently working to contain a fire that was 30-40 acres in size as of 6:45 p.m., Natrona County Fire Protection District firefighter Darek Pepple said.

The larger fire is roughly five miles to the west of Cole Creek Road, Pepple said.

Crews from the Natrona County Fire Protection District, Bar Nunn and the Bureau of Land Management are on-scene.

There isn't a timeline for when firefighters expect to have the fire contained.

K2 Radio News will update this story when we know more.