A Delta Air Lines passenger jet on its approach to Chicago’s Midway International Airport was hit by fireworks during the United States’ 250th-anniversary celebrations, authorities and the airline said.

Delta Flight 1076, traveling from Atlanta, reported that a fireworks mortar struck the aircraft while it was on descent just before landing around 8:30 p.m. local time on July 4. Air-traffic control audio indicated the crew felt a “big bang” and initially hoped it was a mortar that went off beneath the plane.

The Airbus A319 landed safely and taxied to the gate. The airline said there were 52 passengers and six crew members and that no injuries were reported. Chicago police said the incident caused minor paint damage and referred additional questions to the FBI, while the aircraft was evaluated after landing to confirm there was no further damage.

The incident occurred amid nationwide fireworks displays tied to the independence milestone, including large public shows and additional private fireworks in many areas.