The US is now launching its first-ever air strikes in Syria against the terrorist group ISIS, the Pentagon announced at about 9:30 pm EST, revealing that the US military is "using a mix of fighter, bomber, and Tomahawk Land Attack Missiles" along with the air forces of Middle Eastern allies.

But the news was actually broken 30 minutes earlier by a Syrian Twitter user in the city of Raqqa, where ISIS has its headquarters, who heard the strikes and speculated — correctly, it turned out — that this was the beginning of the American air campaign. The Twitter user, named Abdulkader Hariri, posted that "massive" explosions had rocked ISIS headquarters, and that the skies were full of war planes and drones. Here are his tweets, which are chilling to read:

Breaking: Huge explosions shook the city in what might be the beginning of US airstrikes on ISIS HQs in Raqqa — Abdulkader Hariri (@3bdUlkaed6r) September 23, 2014

The airstrikes 5/6 concentrated near the 'governorate building' ISIS's main HQ. Meanwhile, sounds of warplanes can be heard clearly — Abdulkader Hariri (@3bdUlkaed6r) September 23, 2014

The sky is full drones over Raqqa now — Abdulkader Hariri (@3bdUlkaed6r) September 23, 2014

Reports of similar airstrikes on Tabga town and brigade 93 in Ein Essa. — Abdulkader Hariri (@3bdUlkaed6r) September 23, 2014

The air strikes are a major escalation for the United States against ISIS, which has effectively erased much of the border between Iraq, where the US has been bombing it for weeks, and Syria, where Obama has been more reticent to intervene. Here also is an eerie video, quickly posted by the Syrian activist news agency Step, that purports to show those first strikes over Raqqa.

These tweets and videos, posted by Syrian activists bearing witness to American strikes in their backyards, are only going to get more common as the US air campaign accelerates.

The US is bombing Syria to destroy ISIS. Here's why that almost certainly won't work, explained in 2 minutes: