Joe Sullivan, chief of the Homeland Security unit, said a 26-year-old Philadelphia-area man who rented the room Friday night was in custody and would probably be charged. The narcotics unit is seeking a second suspect, he said.
Most guests were provided shelter in the neighboring Convention Center, Sullivan said, and were able to return to their rooms by about 8 a.m., with the exception of seven rooms kept vacant for the difficult and expensive cleanup.
The hotel has 250 rooms and was about 60 percent full Friday night, a hotel worker said.
Hotels and motels are increasingly used by meth-makers because the chemicals used - which can include lighter fuel, lye, lithium, and acetone, among other dangerous substances - seep into fabrics, furniture, and floors, according the Department of Justice website.
"It's popular to do this," Sullivan said. "You basically destroy someone's hotel room, and then you leave."
The single-pot method uses a combination of chemicals shaken up in a plastic bottle, with explosions sometimes resulting.
Professional cleaners are required to make the room safe. In this case, the hotel and the city Department of Licenses and Inspections will oversee the cleaning, authorities said.
Some of the guests were out-of-town firefighters, in town for the International Association of Firefighters convention, which ended Thursday, Sullivan said.
"Certainly, it is really disturbing that this is the experience they have in Philadelphia," Sullivan said. "The actions caused a lot of damage, and not all of it is tangible, but it's serious nonetheless."
Had authorities not found out about the lab and the men conducted their business without detection, the chemical residues would have endangered any subsequent guests, especially children, according to Sullivan.
"Thank God we're aware of what occurred in there," he said. "This is a very serious matter that had very serious implications for the future."