AMMAN, Jordan — The tourists never saw the gunman coming. After viewing Amman’s Roman amphitheater in the midday heat, they were climbing the ancient steps leading up from the stage when he came at them from behind.

“The first I heard was a popping noise that sounded like a firework,” Karen Sparke, 47, of Salisbury, England, said. “We all turned round and looked back down the steps, and the next thing I noticed was that I had been shot.

“There was blood everywhere, people shouting, it was bedlam.” Witnesses said the gunman, a 38-year-old Palestinian Arab refugee, was silent before the attack. But then he dodged behind ancient columns still standing in front of the Roman monument before sprinting across the well-maintained gardens of nearby Hashemite Square shouting “God is great” in Arabic.

The attack killed one British tourist, Christopher Stokes, 30. Four women from the group were injured, two from Britain, an Australian, and a New Zealander. A man from Holland and a Jordanian policeman were also injured.

Reloading several times, the gunman carried on shooting for several minutes before he was eventually tackled under a palm tree by a group of hawkers and passersby. “He was a dog,” Shafik Abaadi, 36, who makes a living photographing amphitheater visitors, said.

“A true Jordanian would never do such a thing. I heard from his accent he was Palestinian.”

Mr. Abaadi’s shirt was still grubby with soil from where he took part in the effort to disarm the attacker. Last night, the gunman was being interrogated by Jordanian police.

Mrs. Sparke was speaking from the Prince Hamza Hospital in central Amman where she was being treated for a gunshot wound to her left shoulder.

Her left collarbone was shot away by a bullet that hit her in the back before exiting her chest.

“It was just such cruel luck,” she said. “Our tour party had got to know one another well after traveling in Syria together for several days, and it was just bad luck that the ones at the rear of the group as we left the amphitheater got hit. The man who died was very friendly, a very chatty person.” The tour party was traveling with Imaginative Traveller, a British operator that specializes in inexpensive tours.

The group had already spent several days in Syria and was heading toward Egypt. They had only arrived in Jordan on Sunday overland, and, like thousands of tourists each year, they headed to the famous amphitheater.

Gouged into a hillside in the heart of downtown Amman, the 1,900-year-old masterpiece of imperial architecture is the most famous tourist site in an otherwise modern, sprawling city of hotels, freeways, and apartment blocks.

For tourists, it is a must.

The Jordanian security services, stung by criticism following Al Qaeda’s triple hotel bombing attack in Amman last November, had stepped up security at sites such as the amphitheater.

Uniformed tourist police and intelligence officers in plain clothes patrolled there, but on Sunday, they were unable to stop the attacker.

The suspected gunman, Nabil Ahmed Issa Jaoura, was born in the Baqaa Palestinian Arab refugee camp on the edge of Amman.

Local sources said Mr. Ahmed had spent the last few years living in Zarqa, an anonymous Jordanian town made famous as the birthplace of Abu Musab al-Zarqawi, the jihadist notorious for beheading western hostages in Iraq.

Witnesses said it was only a small weapon, probably a machine pistol, and not as powerful as a Kalashnikov assault rifle. At the scene of the shooting, evidence was left behind of the hasty cleanup job to get rid of the bloodstains. Puddles of soapy water were left drying.