A Greek air force jet crashed at an air show north of Athens on Saturday, killing the two pilots, officials said, as thousands of people were in attendance at the event.

The crash of the twin-seat Phantom F4 jet occurred during a low-altitude maneuver. A fire after the crash sent up large plumes of black smoke. There were no injuries among the spectators.

“The sense of grief is widespread, and our thoughts are with the families of the two pilots we lost,” Prime Minister Kyriakos Mitsotakis said. “It is a reminder of the daily danger faced by Greece’s aviators, who remain on constant standby to protect Greece's skies.”

Air force officials in Greece said the bodies of the two pilots were located during a rescue operation, hampered in the early stages by the fire on the grounds of Tanagra air force base, 60 kilometers (about 40 miles) north of Athens.

Eleven water-dropping planes and helicopters assisted 85 firefighters to contain the blaze, which remained at some distance from the viewing area at Athens Flying Week, an annual air show.

Organizers canceled remaining events planned over the weekend, while the fire prompted an evacuation order in an area near the base.

Video footage of the crash showed a plume of smoke rising from the point of the impact followed by a larger, second explosion that occurred nearby as the plane broke apart.

Cyprus' Defense Minister Vasilis Palmas said that he had called his Greek counterpart, Nikos Dendias, to express the condolences of his government.

“It is with deep sadness that I learned of the death of the two officers of the Hellenic Air Force, who lost their lives in the tragic accident that occurred during the air show at Tanagra Air Base,” Palmas wrote in an online post.

The air force declared three days of mourning following the crash.