A total of 20 women and girls have been killed in Baltimore this year, compared with 22 all of last year, 17 in all of 2011, and 19 in 2010.

Recent victims include 40-year-old Natasha Bates, killed along with her brother in a double shooting in West Baltimore on July 10; Lakeisha Vannison, who police say was killed by her boyfriend in the 1000 block of Pennsylvania Ave. on July 5; and Karolina Derezinska-Szkiluk, 38, who police say was killed by her estranged husband in Highlandtown on June 29.

In addition, Gennie Shird, 20, was one of three women shot on a porch in Northeast Baltimore on June 27, and Donyae Jones, 18, was one of five people shot on North Kenwood Avenue June 22.

Terrena Williams, Diamond's mother, said her daughter grew up in the family's neighborhood and thrived at Mergenthaler.

"Diamond was the sweetest person you could know," she said. "She had a good head on her shoulders."

Van Wert, her teacher, described her as a particularly compassionate teenager who volunteered to take charge of two elementary students at the Special Olympics this year.

"She built a relationship with them within the first 10 minutes she was there and set a good example for everyone."

And when the petite girl studied the Holocaust this year, she pleaded with Van Wert to arrange a trip to the U.S. Holocaust Museum in Washington because she had never been there. When she got there, she was fascinated by the exhibition. "She was very curious about things all the time," Van Wert said.

"She was one of our most promising students," said Angel Watts, an emergency room nurse and a nursing teacher at Mergenthaler. "She had this bubbly, upbeat personality."

When Diamond walked through Mervo's halls, Watts said, she would always say hello, even if she had seen that person a half- hour before. Williams was in a training program to become a nursing assistant and was one of the top students in the class that Watts co-taught.

Watts said Diamond had supportive parents and came to school every day. She was "eager to do what she needed to do to stand out" in her classes.

"She was one of those kids who everybody spoke to. She was such a pleasure to teach. I can't believe this happened to her."

Both teachers said they were shocked. "It just doesn't add up. She seemed like the girl who would stay as far away from anything that seemed like trouble" as she could, Van Wert said.

Damond Williams said his daughter was "bubbly, eager, very opinionated" and was "a mother to all her little cousins, and even some of her big ones."

Many family members live in Baltimore, he said, and they are close-knit. Terrena Williams said her son, 13-year-old Damond Williams Jr., is struggling to cope with the news.

"It's hard for everybody," she said.

"She is just such a good kid. She is going to be missed by a lot of people," said Van Wert.

Baltimore Sun reporter Jessica Anderson contributed to this article.