SAN DIEGO (AP) — An explosion tore through a hotel near SeaWorld San Diego where a couple was allegedly extracting hash oil, sending guests fleeing for safety and putting three people in the hospital, authorities said.

A 22-year-old man in the room suffered life-threatening injuries in the Wednesday explosion at the three-story Heritage Inn Sea World Hotel, authorities said. Also hurt were a woman in the room and a young man staying next door.

Julie Jordan of San Diego was sleeping with a friend's baby in a nearby room when she felt the building shake violently, then heard a loud explosion. She ran outside and saw a shattered window and a badly injured man sitting at the bottom of some stairs, she said.

"There was chaos. I was very confused. When I came out of the room, I didn't know which way to turn," she said.

Another guest, Joseph Tydingco, said "It was like a disaster zone in there."

Investigators found several boxes containing canisters of butane inside the room where the blast occurred, police Lt. Joseph Ramos said.

The butane apparently was ignited by a cigarette, Fire-Rescue Department spokesman Maurice Luque said. The second-floor room looked like a "war zone," he said.

"It was a very intense and devastating explosion," Luque said.

Hash oil is made by packing finely ground stems and leaves of marijuana plants in a pipe and pouring butane through it, said Amy Roderick, a spokeswoman for the U.S. Drug Enforcement Administration, which is leading the investigation. The liquid typically is then cooked on a stove to separate the butane.

Hash oil averages about 15 percent THC, the chief intoxicant in marijuana, according to the DEA. A drop or two is about as potent as a marijuana cigarette.

The DEA did not confirm that a cigarette ignited the butane or know the size of the drug operation.

"It just looks like a bomb that blew up there," Roderick said. "It's hard for us to tell what was going on there."

The DEA will review the evidence before deciding whether to send the case to the San Diego County district attorney's office for criminal charges.

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Authorities said the couple in the room where the explosion occurred suffered burns, and the man in the neighboring room had bruises, cuts and possible burns.

The badly burned man was in "very, very serious" condition, Luque said. His female companion and the man in the next room — both believed to be around 20 years old — were in moderate condition. Their names were not released.

Joseph Tydingco, 52, rushed out of his room after what felt like a major earthquake and saw black smoke billowing from rooms. He grabbed a fire extinguisher and, with another guest, removed mattresses as they heard people screaming outside.

Tydingco, a SeaWorld maintenance worker, estimated that walls collapsed in six rooms. Police said at least four rooms were destroyed or badly damaged.

The blaze was mostly under control within minutes of the blast, which happened at about 11:15 a.m.

Tydingco said the hotel largely caters to vacationing families on tight budgets and local residents who lack enough cash to sign a rental lease.