President Ram Nath Kovind, Prime Minister Narendra Modi on December 13 paid tributes to martyrs of the 2001 Parliament attack that brought India and Pakistan to the brink of war.
"I pay homage to the brave security personnel who laid down their lives on this day in 2001, defending the Parliament of the world's largest democracy against a dastardly terrorist attack. The nation shall forever remain grateful to them for their supreme sacrifice," Kovind tweeted.
Here's what happened on the fateful morning of December 13, 2001:
On December 13, 2001, five terrorists of two Pakistan-based outfits -- Lashkar-e-Taiba (LeT) and Jaish-e-Mohammed (JeM) -- infiltrated the Parliament complex and opened fire, killing nine.
The terrorists were armed with AK47 rifles, grenade launchers, pistols and grenades.
The speeding white Ambassador drove past the main gate of Parliament and drove into Vice-President Krishan Kant’s vehicle convoy.
The terrorists later stepped out of the car and began shooting.
Terrorists entered the Parliament House in a car with a fake identity sticker to breach the security deployed around the parliamentary complex.
Constable Kamlesh Kumari of the Central Reserve Police Force (CRPF) was the first to spot the terrorists and was shot by them as she raised the alarm.
The Vice President's guards and security personnel also shot back at the terrorists and then started closing the gates of the compound.
Ministers and MPs inside the building, including Lal Krishna Advani and George Fernandes, were ferried to a safer location inside the Parliament which was by then put on lockdown.
All five gunmen were shot dead.
The victims included five Delhi Police personnel, CRPF constable Kamlesh Kumari, two Parliament watch and ward staff, and a gardener. A journalist who was injured died later.
Afzal Guru was subsequently arrested in connection with the case from Jammu & Kashmir.
The Delhi HC upheld the death sentence by a trial court for Afzal Guru in 2003, which was upheld by the Supreme Court in 2005.
Shaukat Hassan Guru, who was also arrested in 2001, was given 10 years of rigorous imprisonment.On February 9, 2013, Afzal Guru was hanged at Tihar Jail amid tight security.