First responders have found the bodies of 40 people killed in the collision between a passenger plane and a military helicopter in Washington, D.C., security sources said Thursday, CBS reports.

Some bodies were washed ashore by the waves, while others were underwater in the Potomac River, the source said.

Experts believe that all the remains of the casualties have now been found.

But there may also be dead bodies in the plane’s tail section, which still remains inaccessible to divers, the source said.