A 32-year-old Portland woman suffered a slashed hand Wednesday when a knife-wielding man attacked her as she removed her two young children from a minivan at the Oregon Zoo, Portland police said.

Jere Ryder, 49, a registered predatory sex offender, had approached the woman from behind, ordering her and the children back into the car, said Sgt. Brian Schmautz, a spokesman for the Portland Police Bureau.

The victim fended off Ryder, receiving the slash from the knife, and screamed, attracting the attention of nearby construction workers at the World Forestry Center. The workers chased and captured the man, holding him until police arrived, Schmautz said.

Ryder was charged with robbery and kidnap.

Ryder, who was convicted of rape and sodomy in 1974, is prone to targeting women who are strangers, entering residences at night and threatening victims at knifepoint, according to his online predator profile.

"We've been actively trying to find this guy because he had two warrants out for failing to register as a sex offender," Schmautz said.

Ryder's last known address was in Beaverton.

Oregon prison officials said Ryder was paroled in August 1981, but returned to prison after being convicted of burglary in October of that same year. He was released from Oregon State Penitentiary in 2001.