Police in Falls Church, VA evacuated an office building that houses an abortion clinic for the second time Thursday, NBC’s Julie Care reports.

The second evacuation comes after Falls Church police and fire units responded to sounds of an explosion around 9 a.m. Fire investigators told the Falls Church Patch they found exploded fireworks in the elevator, and re-opened the building around 9:30 a.m.

Following reports of a second incident Thursday afternoon, Falls Church Police reportedly taped a message to the door saying the building was closed for an investigation into a possible bomb threat.

Falls Church Healthcare Center abortion clinic is located in the building, and frequently draws protests from anti-abortion organizations. As Falls Church News-Press reports, “last month, a 50-person prayer was held outside the building for the ’40 Days of Life Campaign.’”