A tragic accident involving a construction crane made national news last April. Reportedly, the crane collapsed over a downtown street in Seattle, Washington, killing four people and injuring numerous others. New Hampshire residents, especially those who work in construction, may find the subsequent findings regarding this tragedy interesting.

According to Construction Dive, a crane inspector says most accidents involving these massive pieces of equipment are due to human mistake, rather than unavoidable equipment failure. The most common avoidable mistakes involving construction cranes include failing to properly operate, inspect or maintain the machinery. As of last April, the U.S. Occupational Safety and Health Administration has enacted new regulations that require construction crane operators to be certified and licensed to operate specific crane types, as well as to receive ongoing training to be permitted to operate new equipment.

The accident was determined to have been caused by pins being removed from the crane too quickly as workers began disassembling the crane, a violation of the equipment’s safety rules, reported USA TODAY. A gust of wind caused the unsecured crane to fall. Three companies have been fined for failing to follow safety procedures and ensure workers adhered to the rules.

This tragic event illustrates how a serious construction accident might not only harm construction workers, but can also endanger the lives of innocent bystanders. Only two of the people killed in the Seattle accident were employees of the construction companies. The other two were driving vehicles on the street below. Construction companies and those working for them have a responsibility to ensure safety standards are met so people can be kept from harm.