A teen was killed and six other young people were wounded — one critically — in a mass shooting that marred Memorial Day early Monday in Michigan. Police in Lansing said the gunfire that erupted in a downtown park around 2:50 a.m. was “believed to be an isolated incident,” according to reports. No one was arrested and an investigation was ongoing. The dead teen was identified only as a 17-year-old boy and the other victims were 15 to 20, local TV station WLNS said. Mayor Andy Schor blamed the bloodshed on “people using guns to settle arguments.” “The fact simply remains that access to guns is …