Two Italian military personnel on a weekend patrol have disappeared in western Afghanistan, and police said Sunday they were searching for the pair and their two Afghan staff.

In northeastern Afghanistan, meanwhile, NATO helicopters fired on a group of suspected insurgents in response to a rocket attack. Four Afghans died and 12 were wounded, the alliance said, and officials were investigating whether the dead and wounded were Afghan police or civilians targeted mistakenly.

An official from the Italian embassy in Kabul said the two missing Italians last spoke with officials at their base on Saturday night during "routine contact." The Italian military in Herat was trying to reach them again.

The two Italians, with their Afghan driver and translator, drove through a police checkpoint in the Shindand district of Herat province on Saturday, and they have not had any contact with anyone since, said Gen. Ali Khan Hassanzada, chief of police criminal investigations in western Afghanistan.

Hassanzada said it was not yet known if the four were kidnapped: "We have launched an investigation in the area."

Taliban spokesman Qari Yousef Ahmadi told The Associated Press that he did not immediately know if Taliban militants kidnapped the four. Kidnappings by independent criminal gangs have increased around Afghanistan in recent months following reports that foreign governments have paid large ransons to free kidnapped citizens.

In March, five Taliban prisoners were freed in exchange for the release of a kidnapped Italian journalist. The head of the Italian aid agency Emergency has said the Rome government also paid a $2 million ransom last year for a kidnapped Italian photographer — a claim Italian officials did not deny.

Though the embassy official said the two Italians were soldiers, Italy's Defense Ministry called them "military personnel" and the country's foreign minister called them "Italian functionaries," raising the possibility the two work as intelligence agents.

Conventional military patrols in Afghanistan are typically comprised of several vehicles and many soldiers in case they came under attack. Italian news reports also suggested the two might be intelligence agents or members of special forces.

The embassy official said: "They have patrols like that, weekend patrols. They just disappeared after awhile." The official spoke on condition of anonymity because of embassy policy.

The official said the two are warrant officers who were traveling "with a government interpreter on a military mission."

He said they were based in the city of Herat and were last seen in Shindand.

Last May, Shindand was the site of a major battle in which the U.S.-led coalition said its troops had killed 136 Taliban fighters, though Afghan officials at the time said scores of civilians also had died. The Afghan Ministry of Defense has since said that eight civilians were killed in that battle.

Herat police chief Juma Adil said the Italians were working with a reconstruction team associated with NATO's International Security Assistance Force.

The NATO strike in the northeast was in response to a rocket attack at an Afghan army base in the area.

Initial reports indicated they were Afghan police and road construction security guards "dressed in civilian attire and carrying weapons on an uncoordinated patrol," NATO's International Security Assistance Force said in a statement.

"The 12 wounded are civilians, we know that for sure," Afghan army commander Gen. Qadam Shah said.

Shah said it was not clear from preliminary reports if those killed were insurgents or civilians.

More than 4,400 people — mostly militants — have died in insurgency-related violence this year, according to an Associated Press tally of figures from Afghan and Western officials.

At least 600 civilians have died in the fighting, many of them mistakenly hit in airstrikes by Western forces. Afghan officials have pleaded repeatedly with international troops to coordinate closely with their Afghan counterparts to prevent civilian casualties.

In southern Zabul province, meanwhile, the Taliban kidnapped three Afghan men accused of spying for the U.S. and executed them, beheading one and shooting the other two, said Shamulzayi district chief Wazir Khan. Khan said the men were innocent.