KARAK, Jordan — Gunmen involved in a rare terrorist attack in Jordan on Sunday had a large cache of weapons, explosives and suicide vests in the apartment where they had been living, the country’s interior minister said on Monday.
The discovery of the cache suggested that the men were preparing for multiple deadly attacks.
The gunmen killed 10 people and injured 34 more on Sunday; seven of the dead were Jordanian security officers. The police said they had captured and killed four gunmen. It was not clear if that accounted for all of the attackers, or if more might have been involved.
The Jordanian security services were visible everywhere on Monday in and around Karak, the town where the attack took place, and at an ancient Crusader castle there where the gunmen tried to take refuge.
The violence began when a landlord in the southern town of Qatraneh heard an explosion coming from an apartment in his building. The landlord, who spoke on the condition that he not be named for his safety, said that when he knocked on the door, the tenants told him there had been a gas explosion.
He did not believe them, he said, and called the police to tell them that there was a smell of explosives, of weapon residue and of something burning.
The police demanded entry to search the apartment but were met with gunfire, according to a statement from the public security department. One police officer was killed there, according to the interior minister, Salameh Hammad.
The gunmen fled the scene, the police and the landlord said. They traveled to the ruins of the Karak Crusader castle, a historic site about 30 miles away that is popular with tourists, where they attacked an adjacent police station and then hid in the ruins, firing on police and civilians.
One of the three civilians killed there was a Canadian tourist, identified by Canadian news outlets as Linda Vatcher, a retired teacher from Newfoundland; her son David was injured in the attack. Two Jordanian civilians were killed, the authorities said; their names were not released. It was not immediately clear whether the three civilians died inside or outside the castle.
Mr. Hammad told reporters on Monday that three police officers were killed when the gunmen fired on the security post at the entrance to the castle. He said the police were still working to secure the scene and investigate.
A severely dented and damaged white car could be seen in front of the police station on Monday; a security officer confirmed that it had been rammed by some of the gunmen.
Inside the bare apartment in Qatraneh, little could be seen besides broken glass from the shattered windows, a pile of blankets, empty beverage containers and other rubbish. There was no furniture. Spots of what appeared to be blood were visible on the building’s stairwell.
Terrorist attacks in Jordan, an important regional ally of the United States, are relatively rare. Even so, the country is constantly on alert because of the threat posed by extremists, notably those of the Islamic State in neighboring Iraq and Syria.
Mr. Hammad said the gunmen were part of a terrorist cell that was targeting the Jordanian security services. But he said it was not yet known what the attackers’ motives were, and he did not give their names, nationalities or other details about them.
A retired army officer, Hussein Majali, said on Monday that he had been near the castle ruins when the shooting took place and had heard the gunfire. “It was so loud,” he said, that “you would never hear someone’s voice.”
He said civilians, including young men from Karak and local tribal leaders, some of them carrying weapons, had rushed to aid the police in locating the gunmen. They could be seen in videos taken by Karak residents and posted on local news websites.
“If it wasn’t for the professional work of the security forces,” Mohammad Momani, a government spokesman, said during a press conference on Monday, “we would have seen many more deaths.”
Because of an editing error, an earlier version of this article misattributed a quotation about the attack in Jordan. Mohammad Momani, a government spokesman — not Hussein Majali, a retired army officer — said: “If it wasn’t for the professional work of the security forces, we would have seen many more deaths.”