Four people hospitalised after ingesting substance at dance music festival Listen In

Four people have been hospitalised after becoming ill at a dance music festival on Friday night.

Three people are in a critical condition, while a fourth is in a serious condition, after attending the Listen In Festival at Mt Smart Stadium. 

A St John spokesperson said four people became ill from something they ingested at the event, but paramedics don't know what it was. 

"Unless someone tells us, we have to just treat it as a poison. Friends are reluctant normally to tell us so we have to treat the symptoms."

An Auckland District Health Board spokesperson told Newshub the three that were in a critical condition on Friday night are now stable.

The spokesperson said it's hard to track the statuses of everyone that came in from the event because multiple people needed treatment last night.

Ingested substances weren't the only problem the festival had after some attendees got a bit too adventurous.

The festival boasted Australasia's largest marquee, which was erected on the pitch at Mt Smart on Thursday.

Video sent to Newshub shows concertgoers climbing the marquee and playing on it as other attendees watch on.

Three people can be seen galivanting on the roof in the video while the party continues underneath. The marquee reaches about 25 metres in height.

Other video sent to Newshub shows attendees climbing the support beams for the marquee while the music plays.

A police spokesperson told Newshub officers were in attendance throughout the entire event but there were no major issues reported.