A 35-year-old homeless man was seriously injured after a male suspect allegedly used a slingshot to rob him in Honolulu Thursday.

The robbery occurred at or near the grounds of the Hawaii State Library at about 7:35 a.m.

Honolulu police said the suspect on a bicycle used a slingshot and took the victim’s backpack.

The suspect and victim are not known to one another.

Honolulu Emergency Medical Services personnel treated the victim who sustained injuries to his head and leg. He was taken in serious condition to a hospital.

Police have opened a felony robbery investigation. There are no arrests as of this morning.

The suspect was described as 5 feet, 6 inches tall and wearing a black shirt and black pants at the time of the robbery.

Anyone with information may call CrimeStoppers at 808-955-8300.