Many of those who were killed were tourists enjoying a sunny fall afternoon. Among them were five Argentines here for a high school reunion and a Belgian citizen, according to officials from those countries.

Here’s what we know about the attack as of this morning.

What: A man in a Home Depot rental truck barreled down a bike bath near the Hudson River, striking pedestrians and cyclists before crashing the truck into a school bus, officials said. He jumped out of the vehicle with a pellet gun and a paintball gun in hand, shouted “Allahu akbar” (“God is great” in Arabic) and was shot by an officer, authorities said.

When: The attack began just after 3 p.m.

Where: The driver entered the West Side Highway bicycle path at Houston Street and began driving south. His truck collided with a school bus at Chambers Street, nearly a mile away.

Who: Officials identified Sayfullo Saipov, 29, who moved to the United States from Uzbekistan in 2010, as the driver of the truck. He had apparently lived in Paterson, N.J., and Tampa, Fla. After he was shot in the abdomen by the police, he was taken into custody and transported to a nearby hospital. He remained in stable condition as of early Wednesday morning, according to the police.

Why: It is still not known what motivated the attack. Investigators found handwritten notes in Arabic near the truck that indicated allegiance to the Islamic State, but they are treating the episode as a case of an attack “inspired” by the group.