BEAVERTON, Ore. -- Law enforcement is growing more and more concerned after the fourth hash oil explosion in the last year.

The most recent explosion happened late Wednesday night inside an apartment off Southwest Lombard Avenue in Beaverton.

“We heard a thud,” said neighbor Justin Ross. “We heard somebody, a high-pitched noise, like a scream.”

Ross knew something bad happened but didn't exactly what it was. Eventually, police revealed there was an explosion as someone was making hash oil, a concentrated form of marijuana.

“If it was bigger, some shrapnel could’ve come across the street and damaged my house and hurt my kids,” said Ross, a father of two.

The Wednesday night explosion was not the first in Beaverton. In April, there was a hash oil explosion that knocked a garage door off a home. Authorities say there were two other explosions not too far away. All four happened within the last year.

Related: Hash oil explosion blows up Beaverton garage, 1 arrested

“It’s very concerning,” said Ross.

Ross’ neighbor, Troix Chandler, is behind bars facing charges. A second man, Christopher Gibbons, will be booked into jail after he is released from the hospital.

“You don’t know what they’re doing in the house next door,” said Ross. “You assume they’re good people and doing the right thing.”