DAMASCUS, May 23 (Xinhua) -- Three people were killed and 19 others reportedly injured by a blast of an explosive device that ripped through a bus near the Electronic War Directorate just outside the Syrian capital of Damascus on Wednesday, pro- government Sham FM reported.

The report gave no further details.

Also Wednesday, local media said a military overnight bus was targeted by armed groups in Damascus' neighborhood of al-Baramikah wholesale ray ban, which left the driver killed and others injured.

Meanwhile, the state-run SANA news agency said government troops clashed at late time Tuesday with armed groups in Harasta suburb of Damascus, eastern Deir al-Zour and northwestern Idlib provinces, killing five of their members and arresting others.

It said the armed groups have attacked the government troops' posts, triggering confrontations.

Explosions by roadside bombs or improvised explosive devices have become daily occurrences, stocking fears the 15-month unrest in Syria has evolved into revenge crimes.

Most of the explosions and suicide bombings have targeted intelligence and army installations. The Syrian government accuses al-Qaida-affiliated groups of carrying out such attacks.