Chinese officials announced five arrests Wednesday connected to the devastating car attack in Beijing's Tiananmen Square, now designated as a "terrorist attack," that killed five people and injured dozens more.

Chinese state media said that the five people were detained for conspiring to help plan the attack that sent a car full of explosives, machetes and propaganda materials into a crowd in Tiananmen Square on Monday. Three perpetrators were also identified as a husband, his wife and the husband's mother -- they all died in the crash. "The initial understanding of the police is that the Oct. 28 incident is a case of a violent terrorist attack that was carefully planned, organized and plotted," the police said.

The car barrelled into the crowd near Tiananmen Gate Monday, exploding and setting off a chain reaction that injured another 38 people. Along with the three perpetrators in the car, two tourists died in the ensuing chaos.

The five people arrested were all detained within ten hours of the attack, police said, and were all natives of Xinjiang, a northwestern region known for clashes between security forces. Uighurs, the Muslim Turks who live there, oppose Chinese rule, and this is the latest pea in tension between the two sides after a particularly bloody summer