CALEXICO, Calif. (AP) -- There are a lot of jangled nerves in the California-Mexico border region following the latest jolt in an earthquake swarm that's been going on for nearly two weeks.

The biggest one today, measured 5.0 by the U.S. Geological Survey and 5.3 in a seismic network operated by Mexico. It struck at 2:41 local time about 20 miles southeast of the U.S. border city of Calexico. There are no reports of any injuries or damage on the U.S. side.

It was the fourth moderate quake since the swarm began on February 8th.

Some Calexico residents say they're rattled by the current swarm.

The Calexico fire chief says up to 30 residents of a retirement home went outside following one moderate quake last week and refused to return to their homes.

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