 After the third brush fire this week, people living in Del Mar Heights are beginning to wonder if the fires were intentionally set. The most recent fire was contained to around an acre, but the Metro Arson Strike Team is investigating the situation. Longtime resident Wayne Pifer says he saw a pair of 20-year-old men leaving the scene of one of the fires with a container of liquid. Torrey Pines State Natural Preserve is closed to visitors for the investigation.