Police working to identify five men killed in an explosion at an industrial unit in Lincolnshire say they believe three victims were from Lithuania.
The five men are believed to have died instantly in the force of the blast in Boston on Wednesday.
The results of post-mortem examinations are expected later. A sixth man survived after suffering 75% burns.
Lincolnshire Police said the men they have "tentatively identified" were 24, 26 and 32 years old.
They said an unidentified spirit may have been produced illegally at the site.
Supt Keith Owen said: "What I can confirm is that we have found chemicals on the premises which tend to indicate either the manufacture or production of alcohol."
Officers have been unable to speak to the sixth man who underwent surgery at the Queen Elizabeth Hospital in Birmingham.
Supt Owen said: "We are working to identify those unfortunate people who died and a main, but not exclusive line of inquiry is the manufacture of alcoholic drinks."
He said police had dealt with illegal alcohol production in the area earlier this year when six stores in the town were found to be selling 'Isopropyl' alcohol, used as a solvent and cleaning fluid.
Boston Borough Council's licensing committee revoked the alcohol licence of one store and suspended another. Action is due to be taken against the other four.
Investigations continue at the scene, where the fire was so intense the metal door of the unit was buckled and cars parked nearby were damaged.
Supt Owen said: "What we need to appreciate is that these inquiries are going to be very slow and very meticulous."