AMMAN — Three Jordanian intelligence officers and two other security personnel were killed in an attack on their security office in a Palestinian refugee camp outside the Jordanian capital, Amman. One suspect was arrested, officials said on Monday, saying it appeared to be an “individual and isolated act.”

The incident at the Baqaa camp, the biggest of its kind in Jordan, jolted the U.S.-backed Arab kingdom, whose relative stability has distinguished it from its powerful war-ravaged neighbors, Syria to the north and Iraq to the east.

Initial investigations suggested the attack at the intelligence department’s office at the Baqaa camp was an “individual and isolated act”, Jordanian government spokesman Mohammad al-Momani said. He gave no further details.

Earlier, when Jordan announced the incident, Momani described it as a terrorist attack that took place at 7 a.m. locally, adding that alongside three officers, a guard and a telephone exchange operator at the security office were killed.

Two residents said the suspect was a 22-year-old Palestinian from Baqaa camp with no Islamist leanings. They said he was seen acting suspiciously in a disused mosque in the area and when he tried to resist arrest, shot at someone, injuring him lightly with a pistol believed to have been used in the attack.

A large proportion of Jordan’s more than 7 million people are descended from Palestinian refugees who fled in the aftermath of the creation of Israel in 1948.

The incident raised fears among residents of a security backlash against camp residents, who have long complained of suffering discrimination in areas such as jobs.