WASHINGTON - US President Barack Obama on Friday afternoon received further briefing on the deadly mass shooting incident in Aurora, Colorado, and called the local police chief to offer federal assistance.

According to a White House statement, upon his return from a campaign trip in Florida, Obama, along with Vice President Joe Biden, received a briefing on the investigation of the shooting that killed 12 people and injured at least 59 others.

Officials briefing Obama included FBI Director Robert Mueller, Homeland Security Advisor John Brennan, Deputy Attorney-general James Cole, Chief of Staff Jack Lew, Senior Advisor Valerie Jarrett and White House Counsel Kathryn Ruemmler.

Obama also called Aurora Police Chief Dan Oates from the Oval Office, telling the latter that he could expect the full support of the FBI and other federal law enforcement agencies in the investigation process.

The mass shooting, now believed to be the worst ever in US history, occurred in Aurora, a suburb of Denver, early Friday, when a masked gunman released tear gas and opened fire into a crowded movie theater. The suspect, 24-year-old James Holmes, has been apprehended.

The tragedy prompted Obama to cut short his two-day campaign swing and return to the White House earlier on Friday.