Drug overdoses took a deadly toll in Santa Rosa over the weekend. Police are investigating the deaths of four young people, and the hospitalization of two more, to see if they are connected to a man arrested for selling narcotics,

Their sudden passing has prompted an outpouring of grief and raised urgent concerns about the dangers of fentanyl-laced drugs. As investigators work to piece together what happened, here’s what we know so far.

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