A Concord middle school is alerting parents about an incident in which two female students had a close encounter with two unknown men Monday morning.

El Dorado Middle School Principal Robert Humphrey said a staff member overheard two girls talking in the hallway about the incident, in which two men in black car followed them as they walked to school Monday morning.

The car pulled up next to the girls as they walked near the Safeway supermarket at Denkinger and Clayton roads, according to the girls' account, Humphrey said.

One of the girls said the men asked if they wanted a ride to school, according to Humphrey. Although the girls said "no," the men continued to follow them, later asking, "Are you sure you don't want a ride to school?" Humphrey said.

Humphrey said the encounter is a rare occurrence for the school, one that administrators do not treat lightly. On Monday evening, the school informed the parents or guardians of El Dorado's 1,100 students about the incident, Humphrey said.

Nearby schools were also notified, including Concord High School, Westwood Elementary School, Mountain View Elementary School and Wren Avenue Elementary School.

"We just want to create awareness," Humphrey said. "Sure, this happened in Concord, but it could happen in neighboring cities."

Concord police is investigating the incident.