The State Council declared a three-day period of national mourning for the quake victims starting from May 19, 2008; the PRC's National Flag and Regional Flags of Hong Kong and Macau Special Administrative Regions flown at half mast. It was the first time that a national mourning period had been declared for something other than the death of a state leader, and many have called it the biggest display of mourning since the death of Mao Zedong. At 14:28 CST on May 19, 2008, a week after the earthquake, the Chinese public held a moment of silence. People stood silent for three minutes while air defense, police and fire sirens, and the horns of vehicles, vessels and trains sounded. <answer>Cars and trucks</answer> on Beijing's roads also came to a halt. People spontaneously burst into cheering "Zhongguo jiayou!" (Let's go, China!) and "Sichuan jiayou" (Let's go, Sichuan!) afterwards.
What came to a halt during the moment of silence?
Cars and trucks