The active volcano off the coast of New Zealand that erupted and claimed at least six lives was a disaster waiting to happen, according to an expert.

“What makes it very dangerous is that it’s very remote, it’s 60 kilometers [37 miles] offshore from New Zealand, with no habitation, no emergency services available,” Melbourne’s Monash University professor Raymond Cass told Australia’s ABC News.

There were 47 people on White Island when a powerful volcanic eruption around 2:15 p.m. Monday trapped tourists and sent others fleeing into the sea to escape the scalding steam and ash, officials said.

“Soon as you’re on the island, if there were to be a volcanic incident, it’s going to be extremely difficult to get immediate assistance,” Cass said.

Cass said officials should’ve considered whether to allow visitors to tour the crater, considering its past explosions have been “unpredictable.”

“The people weren’t on the rim, they were actually in the crater and I think that’s the issue,” Cass told the outlet. “You’re in this very confined space and when the event occurs, there would’ve been nowhere to go. There would’ve been huge blocks of rock flying at ballistic speeds, there would’ve been huge amounts of ash so people wouldn’t have known where to go.”