Syria air defences strike back after air strikes by U.S., British and French forces in Damascus, Syria in this still image obtained from video dated early April 14, 2018. SYRIA TV via Reuters TV

DAMASCUS/BEIRUT (Reuters) - A Western attack on Syria hit a scientific research facility in Damascus and Syrian army depots in the Homs area, state media said, and a Reuters witness said the Syrian capital was rocked by explosions as smoke rose into the sky.

The Syrian Observatory for Human Rights said a second research facility was also struck in Damascus, in addition to a third in the Homs area, and five military bases and depots used by elite army divisions in the Mezzeh area of Damascus.

A senior official in the regional alliance that supports President Bashar al-Assad said the attack by the United States, Britain and France would be viewed as contained if it was now over. “If it is finished, and there is no second round, it will be considered limited,” the official told Reuters.

Syrian state TV said air defenses were confronting the attack and had shot down 13 missiles in the Kiswah area south of Damascus. It said a pro-Damascus “anti-terror axis” was confronting the attack, language suggesting that Assad’s ally Russia may be helping to fend off the assault.

State TV described the attack as a “flagrant violation” of international law.

Observatory Director Rami Abdulrahman said all the targeted locations were evacuated three days ago after the Russians told the government they had intelligence that bases including the research centers would be hit. He said there were so far no reports of civilian or military casualties,