Seven people were injured in a three-vehicle crash on Route 128 in Waltham Monday morning, State Police said. The accident happened just south of Exit 26 at 10:50 a.m., said Trooper Todd Nolan. The crash involved a 2008 Chevy Equinox, a 2006 Ford E-350 van, and a 2012 Ford Escape, Nolan said. Two people in the first vehicle and five in the van were injured, he said. All were taken to Newton-Wellesley Hospital with injuries that were not considered life-threatening.