Boston explosions: Los Angeles, New York City, and London have stepped up security in the wake of two explosions near the finish line of the Boston Marathon.
(AP Photo/Charles Krupa)
Los Angeles police Lt. Andrew Neiman said the department was urging officers to be extra vigilant around large crowds and would increase security at sporting events such as the Los Angeles Dodgers game Monday night.
The department was also activating its emergency operations center to increase communication and increasing patrols for transit and other critical areas, Los Angeles County Sheriff's spokesman Steve Whitmore said.
Police in Washington, San Diego, Vegas and Atlanta were monitoring events closely and assessing potential increases in security measures. Agencies were also stepping up social media response, telling the public via Twitter and Facebook to report suspicious activity to the police.