Cupertino (California), March 16 : An Apple campus here was partially evacuated after an envelope containing a white powder substance was discovered by first responders, the media reported on Wednesday. According to a report in NBC Bay Area, emergency personnel from the Santa Clara County Fire Department attended to a possible hazmat situation but found nothing dangerous. "Officials later deemed the situation under control and said employees could go back inside. Officials did not immediately say what the substance was," the report noted. Apple told employees at Apple Park that "authorities concluded that there was no presence of hazardous materials," according to an email obtained by The Verge. The email says that operations were back to normal, and that "all sections are open." Apple did not immediately commented. Tech giant Apple's employees will start to return to offices on April 11. According to reports, the news came more than two years after the majority of Apple's corporate workforce started working from home because of the Covid-19 pandemic. The move signals that big employers in California are comfortable enough with risks regarding Covid-19 infection to reopen offices as cases drop in the state and across the country. The global return-to-office plan for Apple comes after Google said this week that its employees would return on April 4. Apple was one of the first companies to tell its employees to work from home in March 2020, even though the company's culture emphasises in-person collaboration and that the development of new hardware products is best performed by on-site employees. Apple's retail stores are now open around the world. /IANS