A driver plowed a pickup truck down a crowded bike path along the Hudson River in Manhattan on Tuesday, killing eight people and injuring 11 before being shot by a police officer in what officials are calling the deadliest terrorist attack on New York City since Sept. 11, 2001.

The rampage wrecked when the motorist — whom the police recognized as Sayfullo Saipov, 29 — shattered into a school bus, jumped out of his truck and ran up and down the highway waving a pellet gun and paintball gun and up roaring “Allahu akbar,” Arabic for “God is great,” before he was shot in the belly by the officer. He stayed in critical condition on Tuesday evening.

Mayor Bill de Blasio affirmed the rampage a terrorist attack and federal law enforcement authorities were leading the inquiry. Investigators revealed handwritten notes in Arabic near the truck that indicated allegiance to the Islamic State, two law enforcement officials said. But investigators had not exposed evidence of any direct or enabling ties between Saipov and ISIS and were treating the attack as a case of an “inspired” attacker, two counterterrorism officials told.

De Blasio said at a news conference, “Based on the information we have at this moment, this was an act of terror and a particularly cowardly act of terror aimed at innocent civilians.”