A 17-year-old from Prince William County is the second concertgoer to die of an apparent drug overdose after a dance party Friday at Merriweather Post Pavilion, the Howard County police said.

They said the teenager, who was from Woodbridge, Va., was taken to Howard County General Hospital from Merriweather Post Pavilion in Columbia, Md., during the “Mad Decent Block Party” music festival.

Police said the youth died at 7:30 p.m. Sunday. His name was not being released, at his family’s request.

Earlier, a 20-year-old man from Raleigh, N.C., was pronounced dead after being taken to the hospital from the festival. His death was also suspected of being the result of a drug overdose, the police said.

Police said Sunday night that they do not think that the two knew each other.

Police said they will wait for autopsy and toxicology information from the medical examiner’s office to determine the precise cause of death.

About 20 others were also taken to the hospital, many with drug-related symptoms, the police said. All of them were treated and released, the Howard police said Sunday night.

They said that after investigating, they think that the most commonly used drug at the event was MDMA, which is commonly referred to as ecstasy or as Molly. The scientific name is 3,4-methylenedioxy-methamphetamine, the police said.

Police said that information from the National Institute on Drug Abuse describes MDMA as a synthetic, psychoactive drug that has similarities to stimulants and hallucinogens.

According to specialists, the drug can increase heart rate, body temperature and blood pressure.

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