At least 10 people, including a police officer,were killed in a shooting at a supermarket in the US city of Boulder, Colorado and a suspect who was injured in the incident was arrested, according to officials. Al Jazeera reports that the shooting occurred at about 3pm local time on Monday at a King Soopers supermarket in the Table Mesa area of Boulder, a city at the eastern foot of the Rockies about 45 kilometres northwest of Denver. The attack is the seventh mass killing this year in the United States, according to a database compiled by The Associated Press, USA Today and Northeastern University, and follows a March 16 shooting that left eight people dead at three Atlanta-area massage businesses.