NYPD is investigating the brutal assault of a college professor as he walked to his campus on Staten Island.

Police say the 49-year-old man was on his way  to CUNY's College of Staten Island St. George campus when he was attacked by a group of teenagers around noon Wednesday.

The professor told cops — he was in Lieutenant Nicholas Lia Memorial Playground — when he saw several teens setting papers on fire.

When he confronted them, cops says one of them punched him, then the rest of the group also started attacking him.

"That's pretty messed up, you shouldn't do that to somebody," said one man on the street.

"It's a little pause, but that stuff happens everywhere though," said another. "You kind of have to realize we live in a world with danger people."

"It is known kids usually skip classes, they'll go to the park," said a third. "They have a little surveillance but not as much as it should be. It's sad. It's just like amazing what the world has come to."

Police say the victim was taken to the hospital with swelling and bruising.

The College of Staten Island says its providing full support to the professor while he recovers.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-8477, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com.