There has been a major explosion in a Syrian pipeline carrying oil to a refinery near the restive city of Homs. This, as violence from the country's nine-month uprising escalates.

The Britain-based Syrian Observatory for Human Rights confirmed the report, but gave no cause for the blast. The state-run SANA news agency blamed “an armed terrorist group” for the attack, calling it an act of sabotage.

A video on the Internet from opposition activists, and obtained by Reuters, shows massive flames and an enormous cloud of black smoke billowing into the sky outside Homs. Two similar explosions on Syrian oil pipelines occurred in July.

The observatory also said at least seven people were killed by sniper fire and “arbitrary” shooting on Thursday in Homs. A series of kidnappings, random shootings and revenge killings plagued the city earlier this week, as authorities continued their crackdown on pro-democracy protesters.

Syrian President Bashar al-Assad has denied that he ordered the killing of thousands of anti-government protesters. He spoke in an interview with a U.S. journalist aired on Wednesday.

Mr. Assad told ABC News he does not control the forces implementing his country's brutal crackdown. The Syrian leader said there is “a big difference” between having “a policy to crack down and having mistakes committed by some officials.”

The United Nations reports that at least 4,000 people have been killed since the unrest erupted in March.