(CNN) -- German Chancellor Angela Merkel has called for a thorough investigation into the stampede at a music festival that resulted in the deaths of 20 people over the weekend.
In a television interview Merkel said: "Now an intensive investigation is needed to find out what really happened."
And in a statement released by the German government Monday, Merkel added that she was "horrified and saddened" by the tragedy at the Love Parade in Duisburg that also left up to 400 people injured, according to local police.
"Many young people who were delighted to be going to the event have had ... terrible memories and we have to do everything to make sure that something like this does not happen again," Merkel said.
Merkel said the federal administration had offered full support to the North Rhine Westphalia regional government.
The organizer of Love Parade said Sunday that the event would never be held again.
Rainer Schaller said the festival, which began in 1989, has been canceled "out of respect for the victims, their families and friends."
"The Love Parade has always been a peaceful event and a joyous celebration, which will now forever be overshadowed by the tragic deaths yesterday," Schaller said.
The deadly crush happened in an underpass between the main event site and the expansion area. Witnesses told CNN affiliate NTV that people pushed into the tunnel from both sides until it was dangerously overcrowded. The panic began as festival-goers began to lose consciousness as they were crushed against the walls and each other.
Detlef von Schmeling, police president of Duisburg, said 16 of the dead did not die in the tunnel, but at the entrance ramp.
Authorities have identified the victims as 12 women and eight men. Twelve of the victims are from Germany and the remaining eight hail from Australia, the Netherlands, China, Italy, Bosnia-Herzegovina and Spain.
A 21-year-old German woman hospitalized since the incident died of her injuries Monday, bringing the death toll to 20, German officials said.
Duisburg's senior mayor, Adolf Sauerland, said the city had put in place a "solid security plan" and must now begin an investigation into why the incident happened.
"The Love Parade was supposed to be a peaceful and joyful festival for young people from the region and beyond," Sauerland said. "Now this event must unfortunately be considered to be one of the great tragedies in the contemporary history of the city. I am deeply shaken."
Carsten Lueb of NTV said some 1.4 million people showed up at the popular festival, which features dozens of DJs spinning techno music for hours. Organizers expected only 700,000 to 800,000 attendees, so they opened an additional event site to accommodate more people. The numbers are disputed by police, who say the area can hold between 250,000 and 350,000 and at no time was filled to capacity.
Witnesses told NTV that police were warned at least an hour before the incident that the underpass was becoming dangerously crowded. NTV reported that 1,400 police officers were on hand to monitor the event.
Von Schmeling said more than 4,000 police officers provided security for the event. Police are investigating how it came to a back-up in the underpass. One additional entranceway had been opened before the stampede to relieve some of the pressure.