Multiple Kansas City-area school districts canceled summer classes and activities indefinitely Wednesday after word Tuesday of a mass shooting threat in the suburb of Blue Springs.

School was back on for Thursday, however, after the arrest of a suspect was announced Wednesday morning.

At least nine other school districts had quickly joined Blue Springs in its decision Tuesday evening to suspend all summer activities until further notice. Authorities said Wednesday a 19-year-old suspect with ties to the Blue Springs School District had been arrested. 

Blue Springs police notified the FBI after getting a call about 10:30 a.m. Tuesday reporting a threat on SnapChat of “killing people – mass murdering.” The threat was not specific, and didn’t mention a school, police said.

The frightening developments follow a string of mass shootings, including at a grocery store in Buffalo, N.Y., and Robb Elementary School in Uvalde, Texas.

“The safety of our schools will always be our top priority,” the Blue Springs district wrote on Facebook.

“The FBI has confirmed that the individual in question … is dangerous,” the district had posted on Facebook Tuesday night. By mid-morning Wednesday, the district wrote in a new post, “We are pleased to report the situation has been resolved. … We can tell you that the person who made the threat has been taken into custody.  We have been given the all-clear to resume summer school and all school activities tomorrow, June 16th.”