A deadly gun attack at Azerbaijan's embassy in Iran has left one embassy staffer dead and two wounded.

Baku is linking the "treacherous" attack to an "anti-Azerbaijani campaign" in Iran and not buying Tehran's claim that the incident was related to a family conflict.

On January 27, Azerbaijan's Foreign Ministry reported that a man holding a Kalashnikov rifle broke through the security post of its embassy in Tehran at just after 8 a.m. and killed the chief of security. "Two security guards of the embassy were also injured while preventing the attack. Their condition is satisfactory," the statement read. "An investigation is currently underway into this treacherous attack."

In a video circulated on Telegram channels, a gunman is seen abruptly parking his car in front of the embassy, bypassing a security guard, and forcibly entering behind two employees. In another video from inside the entrance, the employees are confronted by the gunman and flee into a side room. The gunman fires shots into the room until another employee approaches him from behind and attempts to wrestle the weapon from him. The video ends at this point.

A suspect was soon arrested by local police. Tehran police chief Brigadier-General Hossein Rahimi told Iranian media that the gunman entered the embassy with his two young children, and that "the preliminary investigation shows that the attacker's motive was personal and family problems." (There are no children visible in the footage.)

According to a Tehran criminal court prosecutor, the detainee claimed that in April last year, his wife "went to the Azerbaijan embassy in Tehran and did not return home." As the individual had not "received any response from the embassy during his repeated visits to the compound in Tehran," he decided to go there with a rifle, the official stated.

The Iranian version was swiftly dismissed by the Azerbaijani media and officials.

The Azerbaijani Foreign Ministry released a statement calling it a "treacherous terror attack" and asserting that Iranian authorities had not taken action after being warned of threats to the embassy. The embassy staff and their families are being evacuated from Iran.

"Unfortunately, the latest bloody terrorist attack demonstrates the serious consequences of not showing proper sensitivity to our urgent appeals in this direction. We are of the opinion that the recent anti-Azerbaijani campaign against our country in Iran has encouraged such attacks against our diplomatic mission," the statement read.

The ministry summoned the Iranian ambassador in Baku, Seyed Abbas Mousavi, and told him that "the perpetrator of the terrorist act [must] be brought to justice as soon as possible, [which Iran must also carry out] a thorough investigation of the terrorist act, identification and punishment of other participants involved in the organization and commission of the crime."

Azerbaijani MP Mader Musayev, who is a member of Azerbaijan-Iran parliamentary working group, told news agency Report.az that the claim of the attacker having a personal motivation was "ridiculous" and "shameful."

"It is not a secret to anyone that recently Iran has not been behaving like a state that can be called a brother. It clearly violates the laws adopted by every country and shows disregard for international law," he said, adding that Iran's Supreme Leader, Ayatollah Ali Khamenei, must apologize to the Azerbaijani people.

Azerbaijani news site Caliber.az, connected with the country's Defense Ministry, went so far as to claim that the Iranian special forces were behind the attack. According to the outlet, the Tehran police's theory is "a fiction and an attempt to present the terrorist attack planned by the Iranian special services as a 'household accident.’"

President Ilham Aliyev "fiercely condemn[ed]" the attack in a tweet, and conveyed condolences to the family of the embassy's slain chief of security, First Lieutenant Orkhan Rizvan oglu Asgarov.

Aliyev himself refrained from blaming Iran for the attack, however.

Ties between the two neighboring Shia Muslim-majority countries have been increasingly tense in recent years and this incident, as the Azerbaijani Foreign Ministry told the Iranian ambassador, has "further strained the already complicated relations."

There are periodically outbursts of discontent with the theocratic regime in Tehran among the tens of millions of ethnic Azeris living in northern Iran, including during the nationwide anti-regime protests that started last September. Last November President Aliyev sent a message to them while speaking at a conference: "We will do our best to protect the secular lifestyle of Azerbaijan and Azerbaijanis around the world, including Azerbaijanis in Iran. They are part of our people."

Azerbaijan has long accused Iran of favoring Armenia in the decades-long conflict over Karabakh – especially after the 2020 war, when Azerbaijan established control over its entire frontier with Iran. Azerbaijan accused Iran of sending oil and other goods to "separatist authorities" in Karabakh.

For its part, Tehran is anxious that a proposed "corridor" connecting Azerbaijan and its Nakhchivan exclave could cut off its access to Armenia and destinations further north. It is even more worried about Azerbaijan's strong and growing friendship with Tehran's archrival, Israel, in particular the prospect of an Israeli presence on its northern border.

Israel was among the first to offer its condolences over the embassy attack.

And hours afterwards, Israel’s ambassador to Baku, George Deek, tweeted about what he called a "very important meeting" with Hikmat Hajiyev, President Aliyev's foreign policy advisor.