Oil prices rose more than 15% at the open on Sunday after an attack on Saudi Arabia’s oil facilities on Saturday that knocked out more than 5% of global oil supply.

According to Reuters, Brent crude futures rose about 19% to a session high of $71.95 a barrel at the opening, while US crude futures rose about 15% to a session high of $63.34 a barrel.

Later, prices were up about 12% after US President Donald Trump said he authorized, if needed, the release of oil from the US Strategic Petroleum Reserve (SPR).

Saudi Aramco said the attack cut output by 5.7 million barrels per day — just as Aramco is preparing for what is expected to be the world’s largest sale of shares.

US gasoline futures jumped 11% and US heating oil futures rose about 6.5% at the open. 

“Even if the outage normalizes quickly, the threat of sidelining nearly 6% of global oil production is no longer a hypothetical, a black swan or a fat tail …” Michael Tran, managing director of energy strategy at RBC Capital Markets, told Reuters.