The Syrian Arab News Agency (Sana) said Sunday's clash "took place while security officials were pursuing the terrorist group that was preparing terrorist acts in the city of Aleppo".
It did not name the organisation but described it as "an armed terrorist group". It said two of the fighters were taken to hospital with severe wounds.
Sana said two security personnel and two civilians were wounded in the clash in the al-Muwasalat area of Aleppo.
Residents said earlier a clash and a car pursuit took place between armed men, thought to be Islamists, and security forces.
Sana also said two fighters were killed and another was wounded in another clash last week. It said the clash and an arms find were not announced then for security reasons.
A human-rights activist said a Syrian court sentenced a man earlier on Sunday to 12 years in jail for belonging to a banned Islamist group.
"The court issued a death sentence against Omar Darwish for belonging to the Muslim Brotherhood organisation in line with decree 49 of 1980 but reduced the ruling to 12 years in jail," activist and lawyer Anwar al-Bunni said in a statement.
A cereal silo was damaged by an
explosion in Latakia
In the early 1980s, Syria crushed an Islamist revolt which led to the death or imprisonment of thousands and drove the Muslim Brotherhood into exile.
Al-Bunni said Darwish returned from Iraq in 2003 after living there for 28 years.
Security forces have clashed with fighters several times in recent months, chiefly during raids to arrest them.
In October, Syria arrested a group of fighters who it said planned to launch attacks inside the country.
Security forces killed a Muslim fighter in September and arrested two in another clash in northeast Syria. A week before, the forces killed five members of an Islamist group in a gun battle in the northwest of the country and discovered a cache of weapons.
In a separate incident, one person was killed and 20 injured by a blast on Sunday in a cereal silo in the port of Latakia, Aljazeera has learned.
A two-storey building, a seven-storey tower and a bridge were destroyed in the blast.
"Technical and mechanical faults were the cause of the explosion," said the local governor, Zahid Haj Musa, quoted by Sana.
"An explosion occurred in a cereal silo causing one death and 20 wounded, of which five are serious," he said.
Transport Minister Makram Obeid said a short-circuit was the likely cause, adding that an investigation was under way, AFP reported.