LONDON -- Londoners were still struggling Monday to take in the cruelty and madness of Saturday's attack.

Eight minutes after it began, it was over. The three terrorists, who were wearing fake suicide belts, were shot dead by police.

But in their wake they left mayhem and a trail of victims who were maimed in their stabbing spree.

One person was heard wailing as first responders treated a bloodied victim who was laying on the ground. Other victims were crushed by the attackers' van on London Bridge.

Imagine the shock and terror of people walking across the bridge on Saturday night when they realized the van was hurdling straight for them at 50 miles per hour -- the driver determined to hurt or kill as many people as he could.

Brad Myers, who was on vacation from Florida, had a narrow escape. After taking a selfie on the bridge, he walked away. Then he heard the van mount the sidewalk.

He took a picture afterward showing bodies strewn on the road.

Brad Myers' picture shows victims who were struck on London Bridge. CBS News

"I do think that everyone needs to see what is going on and what we're up against," Myers told CBS News.

All those who gathered at a vigil today know they're probably up against even more terrorists with London in their sights.

But led by the city's Muslim mayor, Sadiq Khan, they stand determined to face it down.

"I want to send a clear message to the sick and evil extremists who commit these hideous crimes," Khan said. "We will defeat you. You will not win."