Taliban has claimed responsibility for the incident.
The raids in the southern province of Kandahar and the western province of Farah on Monday night came hours after a suicide attacker rammed an explosives-laden vehicle into a U.S. military convoy, wounding four soldiers.
Taliban killed eight policemen in western Farah province bordering Iran late Sunday night, according to a provincial official and the militant group Monday.
According to Kandahar police the attack started last night at about 8:00 pm and lasted for one hour. No coalition forces were killed after the attack, the Military Times reported.
All four injured are in stable condition at USA medical facilities, according to the statement.
Police in the province said that law enforcement officers attacked the Taliban, who "destroyed the checkpoint and took away all the stored weapons".
Kandahar police said that Taliban ambushed security forces check posts in Zhari and Maiwand districts.
The Taliban attacks have not only increased lately, but they are even beginning to employ new tactics.
Farah governor spokesman Naser Mehri told AFP nine Afghan National Army soldiers were killed in two separate attacks in the province bordering Iran that also claimed the lives of at least three civilians.
The suicide bombers had planned to target the district council building and police headquarters using a Humvee vehicle, Durrani said. Later came the reinforcement of the security forces and the checkpoint was repulsed.