A bomb exploded near a highway at the southern edge of Syria's capital Damascus on Sunday morning, state media reported.
An attacker was arrested and no one was injured, state news agency SANA said.
The head of the city's civil defence, Asef Hababe, told Reuters that military technicians had detonated a device.
The Syrian Observatory for Human Rights, a U.K.-based war monitoring group, said the explosion was near a security post.
Syria's war has killed hundreds of thousands of people, forced more than half its pre-war population from their homes and dragged in global powers.
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With Russian and Iranian help, Syrian President Bashar al-Assad's military has beaten back rebels and Islamic State to restore control over most of the country.
A seperate bombing in the northwest Syrian town of Afrin killed three civilians and wounded about 20 on a public bus, several witnesses told Reuters on Sunday.
The blast came on the anniversary of Operation Olive Branch, an air and ground assault launched by Turkey in 2018 on the mainly-Kurdish Afrin to drive out theSyrian Kurdish YPG, which it sees as an extension of the outlawed Kurdistan Workers Party (PKK) that has waged an insurgency on Turkish soil since 1984.
No group has claimed responsibility for the attack.
It follows a blast on Wednesday in Manbij, a northern Syrian town controlled by a militia allied with U.S.-backed Kurdish forces, claimed by Islamic State, which killed two U.S. troops and two civilians working for the U.S. military.