Nearly 3,000 people were killed when terrorists crashed planes into the World Trade Center, the Pentagon and a field in rural Pennsylvania.

People attending a commemoration at Ground Zero observed a moment of silence at 8:46 a.m., the moment the first plane struck. They observed five more moments of silence at the times of the other attacks and the collapse of the towers. Some, including families of the victims, read out the names of those who were lost.

Firefighters come every year to honor the hundreds of colleagues who died trying to save people trapped in the towers.

Edwin Morales lost his cousin Ruben, a firefighter whose body was never found. He said he thinks Ruben’s spirit is still at Ground Zero.

President Donald Trump spoke at a memorial ceremony at the Pentagon, where he recently rolled out a new name. He said, “As one nation, we renew our sacred vow that we will never forget September 11, 2001.”

He also said, “If you attack the United States of America, we will hunt you down and we will find you.” And he added: “We will crush you without mercy. And we will triumph without question. That’s why we named the former Department of Defense the Department of War.”

He emphasized that the US will win every war it fights, including the one on terrorism.