A wildfire in Salt Lake City forced people living uphill from Utah’s state capitol to evacuate, and it remained uncontained Sunday as more than 100 firefighters worked to protect nearby homes.

Helicopters and airplanes were dropping buckets over the flames as ground crews tried to contain the fire on Ensign Peak. Firefighters were working to save homes about 1.2 miles (1.9 kilometers) up East Capitol Boulevard, and evacuees were offered a space in the capitol complex where they could escape the heat.

“With the heat, as well as the wind direction and just the temperatures out here and the fuel moisture, it’s kind of a recipe that we could have a quickly running fire,” Division Chief Bob Silverthorne of the Salt Lake City Fire Department said at a Saturday news briefing.

The first fire crew was dispatched around 4:30 p.m. Saturday and more than six different emergency agencies joined the effort, Silverthorne said.

Police officers knocked on doors to warn homeowners after the fire department ordered a mandatory evacuation for an area of 40 homes on Sandhurst Drive, north of Dorchester Drive. A voluntary evacuation was ordered Saturday along East Capitol. There were no immediate reports of injuries or structure damage, he said.

Officials did not know the exact cause or origin of the brush fire, which grew to 150 acres. By Sunday morning, the Utah Fire Info website listed the blaze as human-caused, and zero-percent contained.

Overall, Utah has had 585 fires burning over 40,000 acres so far this wildfire season, and 421 of them have been human-caused, the website says.