New Delhi, India (CNN) -- Two of India's largest cities -- Delhi and Mumbai -- are on red alert after a shooting at a popular tourist site in Old Delhi left two Taiwanese nationals injured Sunday, authorities said.
Gunmen on a motorcycle fired multiple rounds at a tour bus, Karnail Singh of Delhi police told CNN-IBN.
Police said it happened near a mosque in one of the most populated parts of Old Delhi. The two gunmen fled, prompting the red alert.
"Both the injured are Taiwanese nationals," Singh said. "One of the bullets grazed the head of one tourist and one has been hit in the stomach."
A media outlet in India received a claim of responsibility for the attack, but police are treating the claim with caution.
They think the attack is more likely to be the work of a criminal gang than a terror attack, they said.
The attackers are still at large and police are searching for them, authorities said.
The attack comes two weeks before the Commonwealth Games, which are expected to draw large crowds to the city. Thousands of athletes from around the world will converge on the city October 3.