A woman mourns for victims of the plane crash in front of the presidential office in Warsaw, Poland, April 10, 2014. Poland witnessed the 4th anniversary of the 2010 air disaster in Smolensk, Russia, which killed Poland's former president Lech Kaczynski, his wife and numerous VIPS. On April 10, 2010, a Polish government Tupolev-154M plane carrying then president Lech Kaczynski, his wife and a large delegation of VIPs crashed near a military airfield in Smolensk, killing all on board. (Xinhua/Gao Fan)

A commemoration of the fourth anniversary of the plane crash near Smolensk on April 10, 2010, was held on Thursday morning.

After a mass in the parliamentary chapel, Sejm (lower house) and Senate Speakers Ewa Kopacz and Bogdan Borusewicz laid flowers at a plaque in memory of the 18 parliamentarians who died in the crash.

Prime Minister Donald Tusk, parliamentarians, Warsaw officials and victims' families took part in an official commemoration at the Powazki military cemetery where 28 of the victims are buried.

Defence Minister Tomasz Siemoniak laid flowers and lit a candle at the plaque on the Defence Ministry building, commemorating those victims of the crash who were linked to the military.

Representatives of the Polish Council for the Protection of Struggle and Martyrdom Sites and the Polish Embassy in Russia laid wreaths and lit candles at the site of the crash in Smolensk. Smolensk officials and local Poles were also present.

President Bronislaw Komorowski and his wife Anna, together with the families of crash victims who had a connection to the office of president, took part in a commemorative mass celebrated in the Presidential Palace chapel.

Law and Justice (PiS) leader Jaroslaw Kaczynski, twin brother of late President Lech Kaczynski, together with other PiS politicians laid flowers and lit candles in front of the Presidential Palace in Warsaw.

In Krakow, south of Poland, the late president's daughter Marta Kaczynska laid flowers at her parents' tomb in a crypt under Wawel cathedral.

On April 10, 2010, 96 people aboard Polish President Lech Kaczynski's official Tupolev Tu-154 plane were killed in a crash near Smolensk airport in western Russia. The plane was carrying Kaczynski, his wife Maria and a large number of senior Polish officials.