Ugandan Transport Minister and former Army commander General Katumbawamara was attacked and injured by a gunman, killing his daughter and driver.
According to witnesses, a man on a motorcycle fired several shots at his car near his home in the capital, Kampala.
The military says it is investigating a phone call that may be related to the assassination program.
Soldiers guard a hospital where General Wamara is being treated for a life-threatening injury.
He is considered one of Uganda’s most respected politicians and military personnel.
The BBC’s Patience Atuhaire reports from Kampara, and while such attacks are not uncommon, his attempt to kill his life is a shock.
With a series of tweets, President Yoweri Museveni said there were already “clues” that could lead to murder, and he described them as “pigs” and “terrorists.”
The motive for the attempted killing is unclear.
General Wamara was formerly the Chief of Police and previously led the army.
At the time of the attack on Tuesday, he was traveling in a military vehicle that was hit by bullets from the sides and front.
His daughter Brenda Wamara and his driver, locally named Haruna Kayond, did not survive.
Video footage from the scene in Kiasashi, a suburb of Kampara, shows a former Secretary of the Army visibly shivering, bloody, and rushing to the hospital behind a motorcycle.
Correspondents say the country has been shaken in recent years by shootings by armed men on motorcycles.
In June 2018, politician Ibrahim Abiriga, an ardent supporter of President Museveni, was shot dead near his home.
In April 2017, former police spokesman Andrew Felix Kawisi was killed in a manner similar to a justice of the peace and several Muslim clergy.
None of the murders have been successfully investigated or prosecuted