Four American tourists were among six people killed when an explosion, believed to have been caused by a gas leak, brought down a building in Plaka, the historic Athens neighborhood at the foot of the Acropolis.

The blast struck at about 7:30 a.m. on Friday, September 25. The four Americans, two men and two women believed to be two couples, were staying in a short-term rental on the first floor. An elderly British man and his Greek wife, who lived on the floor above, were also killed.

Rescuers worked through the night with excavators, thermal cameras and search dogs. Crews recovered the six bodies on Saturday. Two women were rescued from an adjacent building, and two neighboring buildings were badly damaged.

Athens Mayor Haris Doukas called it an unbelievable disaster and pointed to a very significant gas leak. The U.S. State Department confirmed the Americans' deaths on Saturday, and U.S. Ambassador Kimberly Guilfoyle said she was deeply saddened.

Residents told reporters they had warned the city and utility companies a year ago about the risk of gas leaks and short circuits in the neighborhood.