June 13 (UPI) -- An engineering professor at a prestigious university in South Korea was injured after being burned by a pressure-cooker bomb found in a package left outside his lab room. The Yonsei University professor had found the box at the door of a fourth-floor laboratory on Tuesday morning, Yonhap reported. {snip} The explosion prompted an evacuation. An investigative team of more than 70 police officers and forensic scientists were dispatched to the site. Large nails that filled the device did not scatter outward because the explosive did not completely detonate.