Denver Public Schools is working with Xcel Energy to figure out what caused an odor late Wednesday morning that led to the evacuation of eight schools in southwest Denver.

DPS says evacuations began around 11:30 a.m. and numerous businesses in the area of South Federal Boulevard and West Evans Avenue were also affected.

“An odor, a really strong odor, and it was making our heads dizzy so we had to evacuate to a bowling alley,” said 13-year-old Jesus Carrillo.

Xcel Energy says 15 workers responded to search for the source of the odor.

Xcel says no leaks were found.

Denver Police and Denver Fire also responded and could not identify the source of the problem.

The schools evacuated were Schenck, Force and Johnson Elementary Schools, STRIVE Prep Federal, Lincoln High and Kunsmiller Creative Arts Academy.

Lincoln’s campus includes Respect Academy and Compass Academy, both of which were also evacuated.

DPS says 17 students from Force, four students from Kunsmiller and one adult from Lincoln complained of feeling ill and were taken to the hospital.

All schools returned to normal by around 1 p.m.

Parents were notified and some decided to pick up their kids early.

"I've never seen anything like this -- such a large area affected by an odor and we don't even know where the odor came from,” said Will Jones, director of Media Relations for DPS. "It's very concerning."