Tianjin residents are up in arms over questions that remain unanswered about last week's massive explosion that has so far killed at least 112 and injured over 700.Residents have been picketing outside the Meihua Hotel, where local government departments have been holding press conferences. Many of the residents live in the residential block near the blast site that was badly damaged when the warehouse blew up.On Sunday, Chinese Premier Li Keqiang arrived at Tianjin, and pledged that a thorough investigation into the blasts would be conducted. He said a central government group has been set up to look into the disaster and that those found responsible would be punished.