Two young boys were injured Monday night during an escape through a third-floor window from an apartment fire in Washington, authorities said.

One child was thrown by his grandmother from a window and caught by a bystander after the fire broke out in the 4400 block of Martin Luther King Jr. Avenue SW, said fire department spokesman Vito Maggiolo.

The second child was in his grandmother’s arms as she tried to get onto a ladder being raised to the window, Maggiolo said. They fell an unspecified distance, he said.

One child was 18 months old and the other was 6, Maggiolo said. It was not clear which was caught and which was carried. The boys and their grandmother were taken to hospitals. The boys had serious injuries.

Maggiolo said the fire broke out in a second-floor apartment, and the children and their grandmother were in an apartment directly above it.

The fire was reported a few minutes before 8 p.m. The cause was under investigation, the fire spokesman said.