The Shulhan Aruch, in the Hoshen Mishpat section (Siman 378), writes that a person is liable for damages that he causes to somebody else’s property, even if the damage was caused unintentionally. The liability imposed by Halacha is so strict that one is held liable even for damages caused due to circumstances beyond his control. For example, if a person innocently slips while walking in the street, and as a result he falls and breaks something that a fellow pedestrian was carrying, he must compensate that person for the loss incurred. Even though the individual certainly did not want or intend to slip, let alone to break his fellow’s property, Halacha nevertheless holds him responsible for the damages he caused.
The exception to this rule, as the Shulhan Aruch discusses (in 378:3), is a situation that can be described as "an act of God," meaning, an occurrence that could not possibly have been avoided even if all reasonable precautions had been taken. An example of this rare situation is a case of somebody who climbs a ladder after carefully checking to ensure that the rungs were sturdy enough to hold his weight. If he indeed ascertained that the rungs were sufficiently sturdy, then even if a rung breaks, causing the man to fall and damage somebody’s property, he is exempt from liability. Since he diligently inspected the ladder before climbing, and the damage was the result of a freak occurrence that he had no reason to anticipate, he is absolved of responsibility. However, if he did not inspect the ladder before climbing, then he is held liable even though he had assumed that the rungs were sturdy enough to hold his weight.
These Halachot demonstrate the extent to which Halacha requires us to exercise care with regard to other people’s property. We cannot use convenient excuses such as "It was an accident," or "I didn’t mean to break it." Halacha is very sensitive to the respect owed to other people’s property, and is therefore quite strict when it comes to damages that a person causes.
Summary: A person is liable to compensate for damages that he caused to somebody else’s property, even if he caused them unintentionally or due to circumstances beyond his control. The only exception is the rare case when a person took all necessary precautions but a freak accident resulted in his causing damage.