Police in Texas are investigating a series of opioid overdoses in Austin which has claimed the lives of at least four people, local officials say, warning drug users not to take unknown substances. Dozens were saved by paramedics. The incident began at around 9 a.m. on Monday when Austin experienced a “sudden surge” in opiod-related overdose calls, with most of them coming from the downtown area. Calls later spread to all parts of the city, including at homes, businesses and areas accessible to the general public. “Upon our arrival, our team swiftly distributed Narcan rescue kits throughout th…