ROME — Genoa paused for a moment of silence in memory of the 43 people who died a month ago when a highway bridge collapsed.

At 11.36 a.m. local time (0936 GMT), the city marked the moment a month ago when the Morandi bridge collapsed, plunging dozens of vehicles into a dry riverbed.

Boat sirens wailed in the Italian city's harbor Friday, while buses switched off their engines and shops closed their doors to remember those who perished.

Prosecutors have been questioning engineers, other experts and company officials trying to determine the cause of the tragedy.

The Italian news agency ANSA quoted Giuseppe Altadonna, whose son, Luigi Matti, died when his truck plunged off the bridge as saying: "We're asking only for the truth."