In two unrelated incidents, a Boston resident who aroused the authorities’ suspicion by carrying hazardous materials and wearing protective gear was arrested at Los Angeles International Airport while two persons were held at Heathrow Airport on suspicion of committing terrorism offenses.

Boston-bound Yongda Huang Harris, dressed in a bulletproof vest and fire-resistant pants, was arrested Friday after the authorities found a smoke grenade, gas mask, leg irons and weapons in his luggage, the Associated Press reported Tuesday citing federal authorities.

Harris is a 28-year-old U.S. citizen whose permanent residence is in Boston. He recently started living and working in Japan. He was arrested on suspicion of transporting hazardous materials from Japan to the U.S., the AP reported citing officials.

Harris was reportedly not co-operative with the federal officials who were trying to interview him. He was not believed to be linked to a terrorist organization but his motive had not been determined, the AP reported.

He was charged with one count of transporting hazardous materials, and his detention hearing was postponed until Friday.

The U.S. Customs and Border Protection officers at the LA airport grew suspicious when they noticed that Harris was wearing the bulletproof vest and fire-resistant pants under his trench coat, which led to a formal investigation by Homeland Security special agents.

Meanwhile, a man and a woman, both aged 26, were arrested Tuesday at London's Heathrow Airport on suspicion of the commission, preparation or instigation of acts of terrorism, the BBC reported. They arrived on a flight from Egypt, British officials were reported as saying by the AFP.

The arrests were part of an investigation into travel to Syria in support of the alleged terrorist activity. According to the BBC, dozens of people are believed to have traveled from Britain to Syria to join the Syrian uprising against President Bashar al-Assad. Some of the groups involved in the fighting are suspected of ties to international terrorism.

British Foreign Secretary William Hague told the BBC that "we've had reports of course of foreign fighters, including British people, going to Syria. That's not something that we recommend and we do not want British people going and taking part in violent situations anywhere in the world, but I can't tell you more about those specific cases."