SAN DIEGO (CNS) - Two 16-year-old boys accused of sexually assaulting two teenage girls in a Rancho Penasquitos park during the Labor Day weekend must stand trial on rape, sodomy by force, kidnapping and other charges, a judge ruled Monday.

Leonel Contreras and William Steven Rodriguez are charged in adult court with 16 counts, including conspiracy to commit a crime, and both face more than 325 years to life in prison if convicted, said Deputy District Attorney Wendy Patrick.

After a daylong preliminary hearing, Judge Frederic Link ruled that enough evidence was presented for the defendants to proceed to trial. A Superior Court arraignment was set for Jan. 9, at which time Patrick said she plans to add several sexual assault counts.

The 15- and 16-year-old alleged victims attended a family party in the 12600 block of Spindletop Road, then walked to a nearby park about 8:15 p.m. last Sept. 3, police said.

The girls -- now both 16 and identified in court as Jane Doe #1 and Jane Doe #2 -- testified that they were attacked from behind by two boys wearing "hoodies" as they sat under a tree.

Jane Doe #1 said she felt a knife to her neck as her friend struggled with a second attacker, identified in court as Rodriguez.

The witness said she and her friend were both taken across the street, up a slope and into a remote bushy area, where she was raped and sexually assaulted by the boy with the knife and a bandana covering his face. She said she was "95 percent sure" that was Contreras.

The witness said Contreras put the knife in his jacket pocket at some point during the 30-45 minute assault.

Jane Doe #1 said the assailants then switched partners, with Rodriguez raping her and Contreras raping Jane Doe #2 nearby.

The witness testified that she asked Rodriguez if she was going to be OK, and he said yes.

"He said, 'I don't want to have to hurt you,"' Jane Doe #1 testified.

She said Rodriguez kissed her, told her she was beautiful "and had he known me before, he would have been my boyfriend."

After the sexual assault, Contreras told the girls to "go back to the party and pretend like nothing happened," Jane Doe #1 testified.

Their assailants led them back down the slope and threatened them before leaving, she said.

"They said that they might not be able to find us again, but if we told anyone they'd find my cousin and hurt her," the witness testified.

Jane Doe #1 said her parents were in the street looking for her and her friend, and the girls told them they'd been raped.

According to court testimony, the girls and the defendants didn't know each other, but Rodriguez lived in the neighborhood where the crimes occurred.

Graffiti found in the area led police to Rodriguez, who told police what happened, according to court testimony. Police then tracked down Contreras, who allegedly said their original plan was to rob someone that night.