PORTLAND, Ore. (KOIN) — The deadly fire that left two men dead in the early hours of July 4 in Northeast Portland was caused by fireworks.

Investigators said the origin of the fire was the Dumpster near the carport. Authorities said this was a complex investigation that included help from multiple agencies, including the ATF.

Seth Robert Thompson and Robert William Gremillion were killed in the Heidi Manor fire. (PPB)

But, they said, determining the cause of the fire is just the start of the investigation. They’re asking anyone who has information to come forward.

“Through the course of the investigation we were able to identify the area of origin as being a Dumpster in the carport area,” said Senior Investigator Jason Andersen. “There’s a sense of relief that we can provide this answer to families. First and foremost, we know that they’re looking for the what. So, to be able to provide that answer in this timely of a fashion is something we’re all relieved with.”

Andersen said he wouldn’t comment on whether there were suspects since it’s an open and ongoing investigation.

“What I can say is while this has been a long week for all those involved, especially the families and those who are investigation, this is the tip of the iceberg on this investigation,” he said.

On Wednesday, officials released the names of the two men who died. Robert William Gremillion, 31, and Seth Robert Thompson, 31, were both killed when the blaze swept through Heidi Manor on NE Weidler.

6 other people were injured, including a 25-year-old woman who is still hospitalized but in stable condition.

Neighbors at the building on Thursday set up a makeshift memorial for the victims, many of them laying flowers near framed pictures of the men.