"Two of these and you'll have to call for backup to get me back."

Behind her she could hear someone get on a radio and call for backup.

If they called for backup now, the situation might spiral out of control.

The two returned fire, took cover and called for backup.

A real cop would have called for backup before coming into the store.

Then he got into the front seat and called for backup.

When it looked good, he should have called for backup.

The terrorist should have called for backup, but he had not.

They couldn't hear them call for backup, but it was moments away.

After being fired on, the special forces moved back and called for backup.