Two Americans were killed last week while fighting with US-backed Kurdish YPG units near Raqqa, ISIS’ de facto capital in Syria.

Nicholas Alan Warden, 29, was killed July 5, and Robert Grodt, 28, was killed on July 6 in the same battle, the YPG said in press release on Tuesday. A British volunteer, Luke Rutter, 22, was also killed on July 5.

Little is known about how they died, but one YPG fighter said the three Westerners were with a small group returning from an operation when someone stepped on a mine and then the group started taking fire.

Warden and Rutter were badly wounded and brought back to the hospital, while Grodt supposedly died in the field, the YPG fighter said.