MILWAUKEE (CBS 58) -- A bizarre attack outside Fiserv Forum, where police say a man climbed out of a manhole, then knocked a 63-year-old man unconscious. 

MCSO

Police say 21-year-old Alandis Tribblett assaulted the elderly bus driver and also bit an officer’s hand.

“The individual lifted the manhole cover out of the street and sat in it,” said John Roots, owner of Natty Oaks.

Roots says the bar had several shuttle buses in the area transporting concertgoers when Tribblett began verbally harassing them.

“He threatened one of the drivers,” said Tribblett. 

When another driver stepped in to help, Roots says Tribblett attacked the driver.

“He assaulted him. Knocked him unconscious and did some hard work to him, I’ll tell you that,” said Roots.

In a criminal complaint, investigators say when they arrived at the scene, the 63-year-old driver was “unconscious and officers noticed blood around his mouth.”

Police say Tribblett was standing by the open manhole and making comments about “underground tunnels where they are sex trafficking kids.”

Natty Oaks

Roots says the driver, who is now recovering, had significant bruising on his ribs, jaw, and head.

“The individual that was assaulted has been with me for an awful long time,” said Roots.

The bar says it's now taking extra security measures when it comes to its shuttle buses and also calling for more security near Fiserv.

“All of our drivers have GPS in our vans, and we have all this ability to see where each other’s at, but we’re investing in bringing security cameras inside of the cabs and cameras outside of these cabs as well,” said Roots. “This is helping people be safe either mentally or physically, by people that are paid to help us and protect us.”

After his arrest, police say Tribblett bit an officer at the hospital. He's due back in court in November.