UPDATE: 1 p.m. EST: GENEVA (Reuters) -- Two Syrians arrested in Geneva Friday had traces of explosives in their car but no toxic gas, Prosecutor Olivier Jornot said at a news conference Saturday.

The two had just arrived in Geneva, he said, adding more arrests were expected in the days ahead amid heightened security in the Swiss city on the French border.

The Swiss attorney general's office had earlier said the suspects were arrested in the Geneva region on suspicion of making, hiding and transporting explosives or toxic gas.

Original story:

GENEVA (Reuters) -- Two people of Syrian origin were arrested in the Geneva region Friday on suspicion of making, hiding and transporting explosives and toxic gas, the office of Switzerland's attorney general said in a statement Saturday.

Criminal proceedings have been opened against the two under a law prohibiting groups such as al Qaeda and the Islamic State Group, the statement said. It did not give names or other details about the two, but said more information would be released later.