A hospital in Yemen supported by Save the Children was hit Tuesday by a deadly airstrike that charity officials blamed on the Saudi-led coalition, an attack carried out on the war’s fourth anniversary.

At least seven people were killed, including four children, when a missile struck a gasoline station only yards from the entrance to the Kitaf hospital in rural northwest Yemen about 60 miles from the city of Saada, Save the Children officials said.

The attack damaged the waiting rooms and occurred at the busiest time of the morning for the hospital, said Jason Lee, Save the Children’s deputy director in Yemen.

He said the organization had lodged a strong protest over the airstrike with the Saudi-led authorities, who had the coordinates of the hospital and should have known to avoid the area.