COPENHAGEN, Denmark — A gunman opened fire in a Copenhagen shopping mall, one of the largest of its kind in Scandinavia, killing an unspecified number of people and wounding several others on Sunday, police said. The suspected gunman, who is in custody, is a 22-year-old Danish man who was detained near the Fields shopping mall on the southern outskirts of the capital, said police inspector Søren Thomassen, head of the Copenhagen police operations unit. “We know that there are several dead” and “several injured,” Thomassen told a news conference, adding that terror can’t be ruled out.