A British tourist has been shot and killed while apparently resisting an armed robbery in a guesthouse in Venezuela where he was staying with his brother.

Thomas Ossel, 28, was fatally shot on Monday night on the island of Margarita, 25 miles north of the Venezuelan mainland.

His brother, Jack, 21, was treated for a stab wound to the back. He remains in Venezuela awaiting the arrival of their father from Britain.

A senior policeman, Luis Garavin, said Thomas Ossel was shot in the jaw during an altercation with three assailants in their hotel, the Casa Rosa. According to local reports, both brothers fought the men.

The robbers tied up several other guests but the Ossels resisted, resulting in five shots being fired.

Peter Eggersdorfer, owner of the hotel, said: "At about 9pm someone rang my bell. That's not unusual so I opened it. After a few seconds there was a pistol against my head. There were seven people, at least one had a gun."

He and several guests were tied up, he said, as the gang went from room to room looking for money. But when they got to the room the Ossel brothers were sharing, they encountered resistance.

"The British people started fighting with the people, I couldn't see, I could only hear," he said. "I could hear shouting of, 'Give me dollars, give me euros.' It was very noisy and lots of action and then I heard shots."

Neighbours of the beachfront hotel in Playa El Agua told a local newspaper that armed robbers targeted areas popular with tourists, who often carry a lot of cash. Garavin said an investigation was under way.

Thomas Ossel came from Cople in Bedfordshire, but worked as a firefighter in Chiswick, west London.

He made constant references to his love of travel on his MySpace page, including a message saying: "Love to travel ... have been to nearly 40 countries now ... would love to make it 100 one day." Messages posted on a Facebook tribute page, entitled Tom Ossel We All Love You, described his enthusiasm and sense of humour.

London's fire commissioner, Ron Dobson, said: "We were shocked and saddened to learn of Tom's untimely death. I know he will be sorely missed by his fellow firefighters."

A family friend, Jacqueline Baxter, described Thomas as "a real adventurer, a real character". She said: "I spoke to Jack last night. He's been coping remarkably well. He was very lucid. I'm sure it will hit him when he comes home."

There are no official government figures for the number of murders in Venezuela. But, according to the Venezuelan observatory of violence – an NGO that keeps track of the figures – the murder rate of close to 50 per 100,000 people is among the world's highest.

Isla Margarita, a sought out travel destination, was visited by about 2.5 million tourists last year, 150,000 of them northern Europeans.

On Margarita alone, three foreign tourists have been killed in 2011. In March, a French and a Belgian tourist were killed in separate incidents.

A Foreign and Commonwealth Office spokesman said: "We can confirm the death of a British national on Margarita island in Venezuela on 18 July. We are providing consular assistance for the family."

Thomas also described himself as a Liverpool FC fan and a keen cook and photographer. "Photography is cool, have taken over 7,000 pics of my travels," he wrote on MySpace.