Mexican officials say police mistakenly opened fire on a family of six after confusing their vehicle with a getaway car being used by armed robbers.

The 13-year-old daughter of the family was shot in the chest and is in serious condition. The father was shot in the shoulder and hand, and the rest of the family members, including children ages 4 and 6, were treated for shock at a hospital.

The shooting happened in the northern city of Monterrey as police chased robbers who had held up a convenience store early Friday morning.

State secretary of security Aldo Fasci Zuazua calls it "an error in police procedure," and says officials are investigating.