WRENTHAM — Marri O’Connell proved at Saturday’s Div. 2 State cross country Championships that she has mastered the Wrentham Developmental Center’s 5K layout.

Racing in chilly conditions on the rolling, sun-splashed course, the Marblehead sophomore built a 50-yard lead with a 5:33 opening mile and was never challenged. She was alone at 2-miles (11:38) and cruised home for an easy 18-minute, 11-second win in the Div. 2A event. The race did lack the early drama of her race at the Kelley Invitational where she lost a shoe, but put it on quickly and ran away from the field for the win.

Her shoes were double-knotted Saturday as she bolted into the lead 100 yards in. “I felt a little off,” O’Connell said. “I wanted to get out fast because of the narrow opening.”

Walpole’s Ila Zollo also broke 19-minutes with her 18:52.8 second-place finish. Minnechaug’s Kay Dickinson copped the bronze medal in 19:23.7. Adeline Lawlor’s 10th-place finish in 20:27.6 paced Melrose to the team title with 86 points to edge Longmeadow’s 90 points and third-place Walpole’s 91 points.

The Div. 2B race proved to be something of an upset as Nashoba’s Caroline Collins pulled away from Lauren Raffetto of Canton in the final 800 to win in 18:21.4. Raffetto finished in 18:23.9 and Holliston’s Maggie Kuchman was third with an 18:30.2.

Defending champion Carmen Luisi of Holliston was in the lead pack through 2-miles before fading to 10th in a still-respectable 19:58.

Collins was happy with her victory over a stacked field.

“I kind of stuck with the pack and it started to disperse the last mile,” said Boston University-bound Collins, who has 5:02 mile speed. “I took off with 800 to go.”

Wakefield scored 91 points to comfortably defeat Newburyport (108 points) and Northampton (111 points) in the team competition.

Marblehead also had a decisive winner on the boys’ side where Isaac Gross opened a huge lead and cruised home in a quick 15:35.7. Gross was well ahead of runner-up Caleb Barnes of Melrose (15:56.4) and teammate Nate Assa (16:12.9). Walpole was an easy winner in the team competition with its’ 71 points.

Gross was extremely happy with his lopsided win. “Totally, by 30 seconds,” he said when asked if his time was a new personal best. “When I race I go purely by instinct. When I got to the first hill I said ‘Isaac you can win this race.’ I talk a lot but just before the start my brain shuts off and there’s no dialogue.”

Nashoba’s star harrier, Adam Balewicz, was victorious in the Div. 2B race. His winning time of 15:34.9 makes him one of the favorites in the Div. 2 race at next Saturday’s Meet of Champions in Devens. Danvers easily won the 2B event with 71 points. Groton-Dunstable put up a miniscule 50 point to win the 2C race. Manchester Essex’s Finn O’Hara was the individual winner in 15:54.9.

Whitinsville Christian’s star harrier Emily Flagg was seven seconds ahead of Georgia Brooks of Groton-Dunstable at 3K and held the lead to the finish. Flagg clocked 18:23.8 for the win. Georgia Brooks of Groton-Dunstable was second in 18:36.2 and Apponequet’s Hailey Desmarais clinched third with her 18:58.8.