UPDATE: LBI Evacuation Underway; Only Westbound Traffic on Causeway Starting at 6 p.m.

A mandatory evacuation is now in effect for all of Long Beach Island ahead of the arrival of Hurricane Irene.

According to a press release, the Long Beach Island Emergency Management Coordinators and local officials decided that the severity of the storm warranted the evacuation, which began at 8 a.m. today.

Originally, officials said that eastbound lanes of the Route 72 causeway would be closed beginning Friday at 8 a.m. That has been revised to Friday at 6 p.m., according to a Long Beach Township official.

Beginning Friday evening, all lanes of Route 72 from Long Beach Island to Route 70 will be open to westbound traffic only to aid in the evacuation, Gov. Chris Christie said in a news release.

Shelters at Southern Regional High School will be open at 8 a.m. Friday to receive evacuees.

By 5 p.m. Thursday, cars were already fleeing the 18-mile-long barrier island. The Wave gas station on Route 72 West in Ship Bottom, the last station before heading over the causeway bridge, was jammed with cars fueling up. Regular and mid-grade gas was already gone.

"Only super, only super," an attendant yelled, referring to premium fuel.

A few blocks away at the Surf City municipal boat ramp, pickup trucks lined up to haul boats out of the water as a light rain fell. Borough-owned trucks were being driven up and down local streets, with a public address speaker blaring the evacuation announcement.

Back in Ship Bottom, the Ocean Bay Supermarket was just about empty, however.

"Have a safe night," owner Robin Oliver was telling customers as she manned a register.

But on Friday morning, said one official, surfers were streaming onto the island to take advantage of big waves heralding the dangerous storm's approach.

Island residents are being asked to secure loose items and check on neighbors before leaving. Local TV channels 22 and 39 and Long Beach Island Information radio station 1650 AM will broadcast emergency information.