West Covina, Calif. ? Residents of an upscale community were on edge Friday as detectives sought whoever shot a neighbor to death in her gated, high-security mansion as she called 911.

Hsiao Hsu, 45, was shot as many as five times just before noon Wednesday, investigators told the San Gabriel Valley Tribune. The woman died at the scene, a nearly 6,000-square-foot home with a tennis court, swimming pool and four-car garage in hills just outside the suburban city of West Covina.

Hsu’s husband, Robert Chien, 44, collapsed when he found out about the shooting and has since remained in seclusion, the Tribune said. The couple’s two children were not home at the time, and Chien was not considered a suspect.

Irene Marquez, who lives next door, said that she doesn’t usually lock her home because she has watch dogs, but that Thursday night her grandchildren were so scared they locked all the doors.

“I’m a little worried. There’s so many places to hide around here – empty lots and wilderness,” Marquez said Friday.

Burglaries in the area are rare, police said. None were reported in February and March until Wednesday.

“I’ve had a half-dozen phone calls from people in the area trying to get more information,” West Covina police Lt. Dan Brooks said Friday.

Authorities said the tape of the 911 call, in which the dispatcher heard two shots, was not likely to be released.

“Probably the first time it’s heard will be (as evidence) in court,” said Los Angeles County sheriff’s spokesman Steve Whitmore.

Hsu was an immigrant from Taiwan and a real estate agent who worked under the name Michelle Chien, said longtime friend Henry Chu of Walnut.

“We all belonged to the Overseas Chinese Youth Association together,” Henry Chu said. “My daughter and her daughter did activities together. Most of us in that group have stayed in touch.”

Robert Chien is president of A-Top Industries, a computer case manufacturer in nearby Industry.

A spokesman for the company, Matthew Mak, told the newspaper that Hsu was “the best human in the world. She helped all the people around her. She was a very, very nice person, the best.”