Observers: Large explosion rocks Syrian capital

Map locates Damascus, Syria; 1c x 1 1/2 inches; 46.5 mm x 38 mm; (The Associated Press)

This frame grab from video provided by the Syrian anti-government activist group Ghouta Media Center, which has been authenticated based on its contents and other AP reporting, shows flames rising after an explosion near an airport west of Damascus, Syria, Thursday, April 27, 2017. Syria's state media reported Thursday that Israel has attacked a military installation near the Damascus International Airport. SANA says Israel fired several missiles from inside the occupied Golan Heights south of the capital at a military installation near the capital's main airport, triggering several explosions and causing damage. (Ghouta Media Center via AP) (The Associated Press)

A large explosion rocked the Syrian capital early Thursday, followed by a fire near the Damascus airport, Syrian opposition activists and a monitor said.

The explosion was heard across the capital, jolting residents awake, the head of the Syrian Observatory for Human Rights Rami Abdurrahman said. He said the explosion was reported to have happened near the Damascus airport road.

The dawn explosion was also reported by other activists' networks but the source was unclear.

Activist-operated Diary of a Mortar, which reports from Damascus, said the explosion near the airport road was followed by flames rising above the area. A pro-government site Damascus Now said the explosion was near the city's Seventh Bridge, which leads to the airport road.

Syria is in the sixth year of a bloody civil war pitting the government of President Bashar Assad and his allies against opposition forces that has left more than 400,000 people dead.

The explosion comes a day after France said that the chemical analysis of samples taken from a deadly sarin gas attack in Syria earlier this month "bears the signature" Assad's government and shows it was responsible.

Foreign Minister Jean-Marc Ayrault said France came to this conclusion after comparing samples from a 2013 sarin attack in Syria that matched the new ones. The findings came in a six-page report published Wednesday.

Russia, a close ally of Assad, denounced the report, saying the samples and the fact the nerve agent was used are not enough to prove who was behind it.

The United States has also blamed Assad's government for the April 4 attack. The Trump administration ordered the cruise missile attack on the air base and issued sanctions on 271 people linked to the Syrian agency said to be responsible for producing non-conventional weapons. Syria has strongly denied the accusations.