RIYADH, Saudi Arabia: A gunman shot dead one American and wounded another at a petrol station in the Saudi capital on Tuesday, in a rare attack on Westerners in the kingdom, police said.
The victims worked for Vinnell Arabia, a US-Saudi joint venture which provides training for the Saudi Arabian National Guard.
US State Department spokesperson Jen Psaki confirmed the incident and said the second American was "lightly injured".
Following the attack near King Fahd football stadium, a shootout occurred between the gunman and security forces, a police spokesman said in a statement carried by the official SPA news agency.
The assailant was wounded and subsequently arrested, police said, adding: "We heard that he's a Saudi national born in the US."
Police said they did not yet know if the incident could be described as a "terrorist" attack.
Two circles of blood, about the size of a hand, stained the ground at the petrol station about 1.5 metres (4.5 feet) from the pumps, an AFP photographer said.
Children showed off a small-calibre cartridge case which they said they found in the same area.
Four police jeeps were stationed on the multi-lane road outside the closed petrol station, within sight of the football stadium.
Tuesday's shooting was the first deadly attack on Westerners in Saudi Arabia since several were killed in a wave of Al-Qaeda violence between 2003 and 2006.
It comes as Saudi Arabia participates in a US-led campaign of air strikes against jihadists of the Islamic State jihadist group (IS) in Syria.
But there was no immediate indication of any links between the attack and the more than three-week-old campaign.
Saudi pilots who participated in the initial late-September strikes against IS received online death threats.
Vinnell Arabia's Facebook page says the firm is "dedicated to providing the best in military training, logistics and support" to the Saudi National Guard, using expertise from former US military and government personnel.
In January, a Saudi court sentenced to death an Al-Qaeda militant and jailed 10 others over a May 2004 attack that killed six Westerners and a policeman.
The defendants, seven of them brothers, were convicted of aiding assailants who attacked a US company in the northwestern port town of Yanbu, killing two Americans, two Britons, an Australian and a Canadian, as well as a Saudi.
Saudi authorities have long feared blowback from jihadist groups, particularly after the attacks of a decade ago, which included assaults on housing compounds where foreigners lived.
One of the compounds attacked at that time housed employees of Vinnell.
Security around Western facilities has since been markedly increased.
Fifteen of the 19 hijackers who took part in the September 11, 2001 attacks on the United States were from Saudi Arabia.
The ultra-conservative Wahhabi Islamic tradition is predominant in Saudi Arabia, where it applies to both religious and political life.
But authorities have expressed concern about extremist ideas luring Saudi youth, some of whom have joined fighters in Syria, where the IS has declared a "caliphate" straddling Syria and Iraq.
The group has been accused of committing a spate of atrocities including crucifixions and beheadings.
Saudi Arabia's top cleric, Grand Mufti Sheikh Abdul Aziz al-Sheikh, in August urged Muslim youth not to be influenced by "calls for jihad ... on perverted principles," and described Al-Qaeda and IS jihadists as "enemy number one" of Islam.