(CNN)Authorities responded Monday to a shooting outside a Des Moines, Iowa, high school that left three students in critical condition, according to fire department spokesperson Ahman Douglass.
Douglass told CNN the victims at East High School included two boys and one girl. All three were taken to area hospitals.
Police started getting calls around 2:48 p.m. CT (3:48 p.m. ET), said police Sgt. Paul Parizek.
Police detained potential suspects, Parizek said.
The school went under lockdown, but students were later dismissed, according to a statement on Twitter from Des Moines Public Schools.
"Des Moines Police and DMPS public safety have given East High School the all clear. Students are dismissing on time," the school district tweeted.
The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) of Kansas City is on scene providing assistance in the investigation, the agency tweeted.
CNN is reaching out to the school district and the police department for more information.
3 students are in critical condition after a shooting at an Iowa high school
4 years ago