A security official has died and two others have been injured following an armed attack on the Azerbaijani embassy in Iran, Azerbaijan's Foreign Ministry said on Friday.
The Azerbaijani Foreign Ministry said in a statement that an investigation was currently underway into the "treacherous attack."
"The attacker broke through the guard post, killing the head of security with a Kalashnikov assault rifle," the Ministry said. Staff at the embassy have been evacuated, according to officials.
"All responsibility for the attack lies with Iran," a spokesman for the Azerbaijani Foreign Ministry told reporters.
Azerbaijian accuses Iran of ignoring security threats
The Ministry added that there had been attempts to threaten its diplomatic mission in Iran before and "measures to prevent such situations and to ensure the safety of our diplomatic missions have been constantly raised before Iran."
The latest attack, Baku said, "demonstrates the serious consequences of not showing proper sensitivity to our urgent appeals in this direction."
Police authorities in Iran said they have arrested a suspect and are investigating the motive behind the attack.
Azerbaijan condemns 'terror' attack
Azerbaijani President Ilham Aliyev called the attack "an act of terrorism" and demanded a swift investigation.
"Terror against diplomatic missions is unacceptable!" he wrote on Twitter.
Iran says attack motivated by personal issues
Video shared on social media showed what appeared to be broken glass and damage to a door inside the embassy building.
Iran's semi-official Tasnim news agency reported that the suspect entered the embassy with two young children. Tasnim reported that Hossein Rahimi, Iran's police chief, told it the attack was motivated by "personal and family problems."
Azerbaijan borders Iran in its northwest and is a close ally of Turkey, Tehran's rival in the Middle East region.
Baku also maintains close ties to Israel, a country that Iran also considers one of its top regional enemies.