Twenty people were killed and 11 others injured in an attack on Chad's presidential palace Wednesday evening, the prosecutor's office of N'Djamena in the country's capital said in a statement on Thursday.

According to the statement, the attack occurred around 7:45 p.m. local time when a group of 24 armed individuals, traveling in a vehicle, pretended to have a breakdown and attacked the guards stationed at the main gate of the Presidency of the Republic.

During this attack, the assailants killed two soldiers and critically injured five others while attempting to breach the premises. Security forces swiftly responded, neutralizing 18 attackers. Six injured assailants were captured and taken to a hospital for treatment.

"These acts of extreme gravity, under criminal law, constitute crimes of murder, intentional bodily harm, attempted disruption of the constitutional order, attacks on state institutions, endangering state security, conspiracy against the state, and participation in an insurrectionary movement," said the statement.

The prosecutor's office has launched an investigation, deploying relevant teams to examine the scene and gather evidence, it added.