I have a city on a 3km-high mountain-top with a population of perhaps 50,000 humans, at a technological level of late renaissance or early steam. Below the city is a coniferous forest with wildlife typical to such forests in Europe, and the base of the mountain is surrounded by a medieval-style curtain wall.
This city has something of a night-life that might be considered unusual for a city in this time-period, but midnight is considered the latest that those not on shift-work might want to stay awake (the city gets a lot of visitors who must leave by midnight or be trapped in the city at least until dawn, which will be no less than 6 hours later, and typically must then make their way home over a considerably greater distance than that travelled to reach the city). Most visitors are typically out of the city by 11-11:30 PM, as they must travel to the base of the mountain in order to leave, and most businesses will close during this time.
For magical reasons, a couple of minutes after midnight on one particular night, the mountain unexpectedly goes into zero-gravity for a period of one minute. For the same aforementioned magical reasons, this is not a localised nullification of gravity, nor does the city move relative to the surrounding air, so there are no atmospheric effects that might otherwise occur if gravity was neutralised - think of this as a city in a bubble being dropped in a vacuum.
The city, its mountain and the surrounding air magically moves from place to place, departing at midnight and arriving at its new location at dawn, and this movement takes the observable form of being lowered into the ground and being raised up in a different place. Normally this does not cause any significant change in local gravity. However, on this rare occasion, one of the individuals who has power over the movement of the mountain delays its departure by a minute, and when the mountain is free to move on, it drops in an event similar to freefall (though into a fourth physical/magical dimension) until it catches up with its intended position in the magical dimension, thus causing this event.
At the start of the event, gravity effectively drops from 1g to 0g over the course of 2-3 seconds, and at the end of the event, about one minute later, gravity ramps back up from 0g to 1g over the same period of time. During this time, there are no vibrations or shocks transmitted through the mountain; the only effect is the reduction of apparent gravity effectively to zero. Since the mountain's surrounding air is magically contained and carried along with the mountain, as if in a dome perhaps 4km high, there will be no loss-of-atmosphere event such as might occur if gravity on a spherical world was locally neutralised.
What would be the effect of this rare event on the city and its inhabitants, as well as the forest and its wildlife be? Would we expect any casualties amongst the human/humanoid population of the city or amongst the wildlife in the forest below?
Despite this event being caused magically, I'm after science-based answers, as few people have magical powers that could affect the situation during this time.
This is a very rare event, having occurred no more than twice in the hundreds of years the mountain has been moving around, and it has not occurred previously in the last hundred years either.