Authorities in Warsaw, the Polish capital, announced an early presidential election would be held soon.
"In line with the constitution, we will have to hold an early presidential poll," Pawel Gras, a government spokesman, said.
"For now, the speaker of the lower house of parliament, Bronislaw Komorowski, is automatically ... the acting president."
The constitution states that the poll must be held before the end of June.
Fifteen parliamentarians were on board as well as Slawomir Skrzypek, the head of Poland's central bank; Andrzej Kremer, the deputy foreign minister; and Franciszek Gagor, the army chief of staff.
Kaczynski's wife, Polish church leaders and families of Katyn massacre victims were also killed.
Sergei Antufiev, the governor of Russia's Smolensk region, told official media that no one survived the crash.
"It clipped the tops of the trees, crashed down and broke into pieces," Antufiev told Russia-24 television.
Dmitry Medvedev and Vladimir Putin, the Russian president and prime minister, offered their condolences to the people of Poland and pledged a thorough investigation into the incident.
'Black boxes' found
Authorities have found both flight recorders, commonly known as "black boxes", from the jet.
"Both the data and the voice recorders were found at the crash site. The analysis of them, which will shed light on the reasons for the disaster, has already begun," Sergei Shoigu, the Russian emergency minister, was quoted as saying by Interfax news agency.
Local authorities said that pilot error may have been the cause of the crash.
"The pilot was advised to land in Minsk, but decided to land in Smolensk," Andrei Yevseyenkov, a spokesman for the local government, said.
Chris Yates, an aviation expert, told Al Jazeera that the Tupolev Tu-154 is capable of operating in extreme weather conditions and able to land on unpaved airstrips.
"These things are built like tanks," he said via email correspondence. "From early reports, it would seem to be a fluke accident."
Komorowski, Poland's acting head of state, declared a week of mourning after the crash.
"We are united - there is no [political] left or right - we are united in national mourning," he said.
Rafal Kiepuszewski, a Polish journalist, said the news came as a shock to the Polish people.
"The fact that much of the Polish political establishment appears to have been wiped out on this single flight has really come as a profound shock to the Polish nation," he told Al Jazeera.
Thousands of Poles prayed, sang and lit candles in front of the presidential palace in Warsaw on Saturday, mourning the president.
Poland had been due to hold a presidential election in October, when Kaczynski was likely to have run against the liberal Komorowski.
|Officials said the plane crashed through
the trees and broke into pieces [EPA]
The conservative Kaczynski, who had served as president of Poland since 2005, had a reputation for being incorruptible and was a popular figure.
Marek Matraszek, a political consultant in Warsaw, told Al Jazeera that politically, Kaczynski had been loosing in popularity recently.
"But even his deepest enemies would not deny that he was hugely respected by the Polish people," he said.
"Many of his political opponents, while disagreeing with him politically, respected him for his career, his personality, his principles ... This will very much go forward into cementing how Poles will remember him: not as a politician but rather as a man of deep principle."
Matraszek said the loss of so many politicians would have a significant effect on the political scene in Poland.
"This is an issue that cuts across political barriers ... Every political party and every part of the political establishment has been affected. These were very senior people with a great deal of experience who will be very difficult to replace ... Many of the people who died had no real successors."