Jordan said on Monday its air force struck what it described as militant hideouts in southern Syria after determining that the suspects behind last week's deadly church attack in the kingdom were linked to "terrorist groups" operating there.
The armed forces said the operation was conducted in coordination with Damascus. There was no immediate comment from Syrian authorities. Five civilians, including women and children, were killed as a result of the Jordanian strikes, a health official told Syria's state news agency.
There was no immediate comment from Jordan on that account.
Hours earlier, senior government security officials said their security forces had arrested two brothers and their brother-in-law after a shootout on Monday over the church violence that killed nine people.
"God willing, they only represent themselves," said Jordan's Director of Public Security, Major-General Obeidallah al-Maaytah.
Such violence is highly unusual in Jordan, a relatively stable US ally in the Middle East. Friday's attack on the Christian minority prompted King Abdullah to order security forces to respond with an "iron fist."
In a press conference, al-Maaytah and Interior Minister Mazen al-Faraya said the country would not tolerate extremist terrorism.
"The file has not yet been closed; investigations are still ongoing. As of today, there are no indications of any links between them and other cells," al-Faraya added.
At least 34 injured after gunmen attack funeral service
Friday's assault during a funeral at a Greek Orthodox church in the village of Hamoud, about 120 km (75 miles) southwest of the capital, Amman, also wounded at least 34 people. Witnesses said gunmen opened fire for several minutes. The suspects, who lived near Hamoud, will face justice, said the security officials. The three suspects were named in the press briefing.
Reuters video footage showed a building pockmarked by the exchange of fire in the village of al-Judayyda, in Karak governorate.
Jordan's Public Security Directorate said in a statement carried by state media that security forces located the suspects while they were hiding in an abandoned house. They refused to surrender and attacked security forces, who returned fire and arrested all three after wounding them.
No security personnel were injured, and security forces found a number of firearms and rounds of ammunition in the suspects' possession.
There has been no claim of responsibility for the church attack.
Jordan, a US partner in the fight against extremism, has foiled Islamist militant plots in the past. The security officials did not name any Islamist groups in the press conference.
Syria condemns strikes, launches investigation
Syria's government condemned the strikes, claiming they had been carried out "without prior coordination or notification from the Syrian side," state-run Sana news agency said in a Tuesday report.
The government also expressed its "full solidarity" with the affected Syrian families and "heartfelt condolences to the martyrs’ families," the report said.
It added that authorities are closely monitoring the situation and will provide "immediate required support and humanitarian relief.
Additionally, it said that "comprehensive investigations" have been launched to "establish the full circumstances of the targeting" and underscored the importance of joint security coordination between the two countries.
Syria also closed the Nassib border crossing with Jordan and suspended passenger and commercial traffic from both sides.