People in Southern California reacted to the United States' killing of al-Qaida leader Osama bin Laden with fireworks and parties, after U.S. President Barack Obama announced the news to the nation late Sunday night.

Scattered fireworks were heard in several communities, including Long Beach, Lakewood and Pacoima, the Los Angeles Times said in a report carried on its website.

U.S. Senator Dianne Feinstein, speaking at a small open-air Santa Monica memorial for California political consultant Kam Kuwata, said at the end of her remarks that bin Laden was dead, the Los Angeles Times reported.

About 25 Jewish students at USC were just finishing a ceremonial dinner at the campus Chabad House when whispers began making their way around the table and diners became focused on their smart phones. ' "Osama bin Laden is dead! It's on Twitter," one student finally said. The room erupted in cheers and high fives, the Times reported.

Scores of jubilant people were seen waving U.S. national flags in Westwood, a suburban area in west Los Angeles, and shouting: "USA! USA!"

In a highly unusual Sunday night speech, Obama hailed the death of the terrorist leader as the "most significant achievement" to date in U.S. efforts to defeat al-Qaida.

"Today, at my direction, the United States launched a targeted operation against that compound," Obama said in a nationally-televised speech.

Osama bin Laden's death is "the most significant achievement to date in our nation's effort to defeat al-Qaida," the president said, and he also warned that "there's no doubt that al-Qaida will continue to pursue attacks against us. We must and we will remain vigilant."

Moviegoers at an AMC movie theater in Monterey Park were excited with the news, as were the janitors and cleaners.

"I went out to the lobby to check out the news," Kevin Song, a Chinese businessman in his 40s, told Xinhua. "Many people around were visibly happy with what they have just learnt from their mobile phones, whispering to each other."

"Tonight, we owe a tremendous amount of gratitude to the brave men and women who serve under our flag around the world, as well as to our Commander in Chief for his unwavering leadership," Los Angeles Mayor Antonio Villaraigosa said in a written statement on the death of the al-Qaeda head.

"This announcement tonight by President Obama that Osama bin Laden has been killed is indeed historic, but we must continue to be vigilant and remain on guard against those that still seek to harm us," he said.

In the meantime, authorities in the Southland have not visibly heightened measures for potential targets against possible retaliatory terrorism attacks, authorities said.

"We have no operations set up at this time," said Deputy Jeff Gordon of the Los Angeles County Sheriff's Headquarters Bureau. "We will deploy all resources and tactical responses necessary if warranted."

U.S. officials cautioned that the operation against the al-Qaida leader could lead to more terror threats against the United States, news reports form Washington said.