CITY BRACES FOR SECURITY BREACHES MORE L.A. POLICE OFFICERS CHECKING SUSPICIOUS TRUCKS.

Byline: James Nash Staff Writer

As authorities secured potential terrorist targets on the East Coast, Los Angeles police on Monday increased their street presence and stepped up truck inspections near financial centers in downtown Los Angeles and Century City.

Local authorities emphasized there was no specific threat against any Southern California target but said they were taking the measures as a precaution.

``This is strictly as a result of what is going on back East and the understanding that al-Qaida has multiple operations going on at the same time,'' Los Angeles Police Chief William Bratton said.

Los Angeles police and California Highway Patrol officers were diverted from normal duties to inspect suspicious trucks in the financial districts, but authorities reported no threats or unusual findings.

Streets in both areas remained open, and there were no incidents reported of excessive absences at high-rise office buildings.

Security was enhanced on the city's rail and subway lines.

The Metropolitan Transportation Authority's chief of transit police assigned undercover officers to key potential targets, but otherwise did not bolster its staffing at Union Station or elsewhere in the public transit system.

At Six Flags Magic Mountain in Valencia, where a steady stream of patrons continued to make Hurricane Harbor a major summer attraction, park visitors encountered metal detectors and backpack checks. The security procedure is not out of the ordinary, Six Flags officials said.

Representatives from the Los Angeles Department of Water and Power, Los Angeles World Airports, Southern California Edison, Universal Studios and Paramount Studios all said their security procedures are in place and that no new measures were started as a result of the new Homeland Security warning.

``We remain on heightened alert. Our security is as tight as ever,'' said LAX spokesman Tom Winfrey.

Officials also announced that on Thursday and Friday they will conduct a terrorism drill involving about 500 law enforcement personnel at the Port of Los Angeles. The exercise, which will simulate the detonation of a radiological ``dirty bomb,'' is unrelated to the heightened security at financial institutions, officials said.

Mayor James Hahn and City Councilwoman Janice Hahn, who represents the port area, said fewer than 2 percent of the 11 million containers that arrive at the port each year are inspected.

``We never know what would happen if we had a dirty bomb in one of these containers, or a rogue ship, unless we practice,'' Janice Hahn said.

Staff Writers Phillip W. Browne, Lisa Mascaro and Susan Abram contributed to this report.

James Nash, [phone]

james.nash(at)dailynews.com