Two U.S. service members were wounded in eastern Afghanistan on Saturday when their vehicle struck a roadside mine, the military said.

They were "conducting a normal security patrol" near the airport on the outskirts of Jalalabad city, capital of Nangarhar province, when "their vehicle hit the improvised explosive device," the U.S. military's spokesman in Afghanistan, Brig. Gen. Charles Cleveland said.

"The individuals were evacuated from the scene of the incident to Jalalabad Airfield for treatment," he said in a statement. The incident happened early Saturday morning, he said.

According to procedure, the troops were not identified.

The incident follows the death earlier this week of a U.S. service member, also in Nangarhar, where American military are involved in counter-terrorism operations against the Islamic State group and the Taliban.

So far seven U.S. service members have died in Afghanistan this year, according to an Associated Press tally.

In violence elsewhere in the country, three Afghan police officers were killed in an insurgent attack on Friday in southern Kandahar province, an official said Saturday.

Samim Khpolwak, spokesman for the provincial governor in Kandahar said that insurgents attacked the police in the Maiwand district. He also said that four other police officers were wounded in the attack.

Other officials say around 20 policemen were killed. They spoke on condition of anonymity because they were not authorized to brief the media. This figure could not be independently confirmed, but officials are often wary of revealing the full extent of the casualties suffered by Afghan security forces in the war with the Taliban, which is now entering its 16th year.

Also in Kandahar, Khpolwak said three children were killed and another four wounded in the Shah Wali Kot district after a bomb they found exploded.