OXNARD, Calif. -- Dallas Cowboys defensive end Tyrone Crawford left practice with a lower left leg injury after he fell down during an individual drill.

Crawford, a 2012 third-round pick from Boise State, banged his fist to the ground while receiving medical attention. Crawford, who was getting second-team snaps on the first day of practice, was carted off the field.

As Crawford was being driven off the field, his head was down and he was covering his face as fans were encouraging him.

It was a long day for the Cowboys in terms of injuries.

The Cowboys are missing five offensive linemen due to injuries, and missing Crawford also thins the defensive line.

Defensive tackle Jay Ratliff missed practice with a strained hamstring, and his return date is unknown. Ratliff underwent an MRI on Sunday.

The other defensive ends on the roster backing up Crawford are Cameron Scheffield and Monte Taylor. The Cowboys might also move a defensive tackle to end.