A memorial service for the 150 victims that died on Germanwings Flight 9525 was held in a cathedral in Cologne, Germany on Friday morning. The Dom Cathedral, as the cathedral is known, is one of the most hallowed cathedrals in the country and one of the largest in the world. Hundreds of mourning relatives attended the ceremony to honor the passengers and crewmembers who died on the flight.

Last month, the Germanwings jet smashed into a French mountainside, instantly killing everyone aboard. The plane was bound from Barcelona, Spain, to Düsseldorf, Germany. About half the people onboard were from Germany, as was the co-pilot, Andreas Lubitz. A subsequent investigation determined that the co-pilot had deliberately brought down the plane, horrifying the world.

It is believed that Mr. Lubitz hid signs of mental illness from his employer, blocked the captain of the plane from re-entering the cockpit during the flight, and set a course to crash the jet into a mountain. Lufthansa, the parent company of Germanwings, suffered a serious blow to its reputation after it was found that Mr. Lubitz had a history of severe depression and the airline had known about it since 2009.

Among the 1,400 mourners in the cathedral were the heads of Lufthansa and Germanwings and a number of invited dignitaries. Many of Germany’s leaders attended the ceremony, including President Joachim Gauck who spoke during the two-hour, nationally televised memorial service. The president was on a state visit to Latin America when the crash occurred. German Chancellor Angela Merkel also attended the memorial service.

There were 150 candles burning in the cathedral during the service, one for each person on the plane, including Mr. Lubitz. President Gauck, formerly a Lutheran pastor in Communist East Germany, spoke of many of the issues that have arisen since the March 24 crash shocked the country. Mr. Gauck said, “We don’t know what was going on inside the head of the co-pilot in the decisive second, in the decisive minutes, but we do know that his family also lost someone they loved on March 24.”