Investigators say a fire that started Wednesday afternoon near Red Rocks Community College is suspicious.

Firefighters kept that blaze under 3 acres and stopped it from damaging anything.

It's one of several fires on the west side of the metro area within the last few months.

Dry conditions and unseasonably warm temperatures led to increased fire danger across the Front Range that sparked two grass fires on Green Mountain in late February.

Back in November, a fire scorched 96 acres and prompted scores of evacuations on Green Mountain, sending a plume of smoke into the air that was visible through much of the Denver metro area.

At this point, investigators say they are still looking into all possibilities and haven't determined if the fires have been accidentally or intentionally set.

West Metro Fire Rescue told 9NEWS determining what caused a fire -- be it humans or nature -- takes several steps.

They say they first search the area for any natural causes, such as a lightning strike, by checking weather reports, or by looking for downed or damaged power lines or leaking electrical transformers.

In some cases, fires have been started by birds who have come in contact with transformers. The bird is killed, set afire and then lands on dry grass. This scenario has not been to blame for the Green Mountain fires.

West Metro says after they determine if a fire is human-caused, they look at evidence that might be on scene: matches, fireworks, cigarettes -- or campfires and also if there are any witnesses.