Four teenagers in Santa Rosa overdosed on suspected fentanyl over the weekend, and two died, police said Sunday night.

Two Santa Rosa high school students have died after allegedly overdosing on fentanyl, Santa Rosa police said. Two other students remain hospitalized after also allegedly overdosing on fentanyl in a separate incident Saturday.

Santa Rosa City Schools sent a message to families Sunday acknowledging that police were investigating the deaths of four students or former students: Saturday’s overdose victims; a 19-year-old former student also thought to have overdosed; and a 21-year-old man believed to have died from natural causes.