CHICAGO (CBS) — Two planes began their takeoffs on intersecting runways at Chicago’s Midway airport on Tuesday evening, before being ordered to stop by air traffic control and averting a collision in the center of the airport, the FAA confirmed.

The two planes involved were Southwest Flight 3828 bound for Tulsa, Okla., and Delta Flight 1328, headed to Atlanta.

“The Federal Aviation Administration is investigating an incident that occurred shortly before 7:40 p.m. Tuesday at Chicago Midway Airport,” the FAA said in a statement.

Preliminary information indicates that the Southwest Flight was cleared for takeoff on Runway 31-Center, the FAA said.