Facebook said Sunday that it removed or blocked from the social media site 1.5 million videos of a gunman's rampage on two New Zealand mosques that killed 50 people and wounded dozens more.

Mia Garlick, spokeswoman for Facebook New Zealand, said that about 300,000 videos were removed within the first 24 hours of the terrorist attack Friday. More than 1.2 million were blocked at upload, she said.

"Out of respect for the people affected by this tragedy and the concerns of local authorities, we're also removing all edited versions of the video that do not show graphic content," Garlick said in a tweet.

Garlick said that Facebook was using technology and people "around the clock" to remove content that violates its violence policy.

Minutes before the attack, the alleged shooter posted a 74-page manifesto on Twitter and sent it to numerous officials and media outlets in New Zealand. The gunman also livestreamed the rampage via helmet cam on Facebook and Twitter.

Footage of the massacre circulated for hours after the shooting, despite efforts by Facebook, YouTube, Twitter and Reddit to take it down as quickly as possible. Twitter and YouTube said they were continuously monitoring and removing any content depicting the tragedy.

"Our hearts are broken over today’s terrible tragedy in New Zealand," YouTube tweeted within hours of the attack. "Please know we are working vigilantly to remove any violent footage."

Twitter issued a statement citing its "rigorous processes and a dedicated team" that activates in such emergencies. The site also stressed that it cooperates with law enforcement investigations.

Church services and candlelight vigils were taking place across the nation of fewer than 5 million people Sunday. Dozens of people wounded in the assault on the Al Noor and Linwood mosques remained hospitalized.

New Zealand Police on Sunday released some details of the initial response to the attack.

"There has been some speculation around the Police response times to the first attack," New Zealand Police Commissioner Mike Bush said in a statement. "To clarify, police received its first 111 call at 1.41pm. The first armed police unit was on scene at 1.47pm. That’s six minutes to respond."

The department's highly trained Armed Offenders Squad arrived with 10 minutes, and the 28-year-old suspect was in custody within 36 minutes, Bush said.

"I am very proud of the police response to this terrible attack," he said.