Seven people have died of suspected drug overdoses during a music festival in Vietnam.

The Capital Police newspaper said five other people were still in comas Monday after overdosing at the festival Sunday night.

The music festival was held in a water park near Hanoi's city centre and attended by thousands of people.

The state-run media outlet said all the victims tested positive but it didn't identify which drug or drugs were involved. It said police had seized suspected drug substances at the scene.

Police and local officials were not available for comment Monday.

Government data say Vietnam has 220,000 drug addicts with police records and some 1,600 overdose deaths annually.

Methamphetamine and heroin are the most common drugs used and overdosed, with meth use rising in recent years.