Officers responded to 23rd Avenue and East Yesler Way just before 5:30 p.m. after getting a call about a potential child luring.
Police say two 12-year-old girls were walking along East Yesler when the man, who has not been identified, tried to lure the girls into his light-colored minivan.
Angelica Harmon's daughter was one of the girls.
"As soon as I pulled up (to the library) the girls ran up to the car and said some guy had opened his door and tried to lure them in," Harmon said. "We immediately called police and it turns out he's a registered sex offender and this isn't the first time he's approached girls in his area."
The man was still sitting in the parked van when police arrived. Officers ran his information and learned he was a registered sex offender.
They took him to the East Precinct to be interviewed. He will then be booked into King County Jail on suspicion of child luring, according to police.
Police say there was no physical contact between the suspect and the two girls.
Harmon said she's just glad her daughter and the other girl were wise enough to run away and get help.
"I don't want anyone to hurt her. I don't want anything bad to happen to her. I'm scared for her and all the little kids out here," Harmon said.
The investigation is ongoing.