AL HUDAYDAH, Yemen — A pharmacist, a delivery man driving a motorcycle and a fishmonger. After an eruption of what aid groups have described as indiscriminate violence against civilians in Yemen’s crucial Red Sea port city, one basic fact is clear: 55 people are dead and 170 others wounded.

Yet like so much of Yemen’s civil war, many elements of the multiple attacks on Thursday remain hazy: who was responsible, and who or what was the intended target. The main combatants in the battle for Al Hudaydah, a city of 600,000 people, have blamed each other for explosions in a residential neighborhood, at the city’s fish market, and outside the main hospital.

The Houthi rebels controlling Al Hudaydah, the country’s vital lifeline for food and medicine, and medics treating the wounded say the Saudi-led coalition launched airstrikes against civilian targets. The Saudis blamed the Houthis, pointing to evidence compiled over the weekend suggesting that mortars, which are launched from the ground, were used rather than missiles from planes.

So far, neither international aid groups nor the United Nations has attributed blame. Instead, they have condemned the attacks as the latest in a litany of assaults, during more than three years of conflict, that appear to violate international laws of warfare.