photo - PAP/Jacek Bednarczyk
The trains, travelling from Przemysl to Warsaw and Warsaw to Krakow crashed at 20.57 CET, Saturday, at the village of Szczekociny, near Zawiercie, Silesia province.
President Komorowski had earlier visited some of the injured at a hospital in nearby Sosnowiec, where he spoke to some family members visiting a woman who had been in the crash.
"I know from personal experience that sometimes contact with the family is [for the victims] important - even the most important, " Komorowski told them.
After less than a half-hour visit at the hospital in Sosnowiec, the president went to the crash site.
President Komorowski said he would soon announce a period of national mourning in memory of the victims of the crash.
“The rescue action is still in progress, so I can only announce today that upon completion of the action […] we will decide on when to declare national mourning,” Komorowski said.
“The scale of the disaster is so huge that it should be a nationwide mourning,” he added.
Earlier, Prime Minister Tusk visited the scene of the disaster, alongside transport and interior ministers.
Speaker of the lower house of parliament, Ewa Kopacz, expressed condolences to the victims' families on behalf of MPs.
"In connection with the tragic train crash near Szczekociny in Silesia, on behalf of members [of the house] I would like to to express my deepest sympathy to the families of the victims and injured in this tragic accident,” she said in a statement on the Parliament's web site.
It has been announced that one of the 15 victims was an American.
“We have identified the bodies of victims of Saturday's train crash [and] among them is a citizen of the United States, Tomasz Ozimek at the district prosecutors offers said, Sunday.
"The victims' bodies have successively been transferred to the Department of Forensic Medicine in Katowice, where he will begin autopsies tomorrow autopsies,” he added.
The rescue operation to free trapped passengers involved 450 fire fighters, 100 police and 35 ambulances.
It is thought 120 passengers were on board the train at the time: 56 were injuured in total, 30 seriously.
Transport minister Slawomir Nowak said it was much too early to conclude what the cause of the disaster was or why the two trains collided head on, on the same track.
“It's one of the worst rail crashes in recent years in our country,” he said.
"It is too early […] to answer the question as to what could be the cause of train crash,” Piotr Kazimierowski, president of the Employers' Union of Rail Transport Forum told the PAP news agency.
“We can talk about three potential causes: technical error, human error or an error in procedure.” (pg)
Last updated 13.51 CET