VANCOUVER — A chemical fire at Vancouver’s port was declared fully extinguished Thursday night after burning for more than 24 hours, allowing investigators to start their work to determine what ignited it.

‍     The shipping container caught fire Wednesday afternoon, sending a plume of white smoke into the air, which prompted health warnings and led more than a dozen people to visit local emergency rooms.

‍     The city’s fire department issued a news release late Thursday night announcing the emergency was over.

‍     “Vancouver Fire and Rescue Services has given the all clear designation and will release fire crews when fire protection services are no longer needed,” said the statement.

‍     Hours earlier, the department said it planned to open the container if the wind conditions were right.

‍     When the fire first broke out, public health officials, police and city staff used bullhorns and social media to tell people to stay indoors and close ventilation systems. The advisory was lifted several hours later, but the local health authority warned people to be on the lookout for possible smoke-related symptoms.

‍     In all, 13 people showed up at hospitals with eye and lung irritation, though none were admitted, and 60 people called poison control, said Vancouver Coastal Health.

‍     “We do expect some people to have delayed effects for up to 24 hours,” said Dr. Meena Dawar, a medical health officer with the health authority.

‍     “As the exposure has passed, I’m happy to report that we’re pleased with how the response has gone.”

‍     Vancouver Coastal Health said any delayed effects would likely only affect people with existing respiratory conditions such as asthma.

‍     Port Metro Vancouver’s Peter Xotta said a container from China held a compound called trichloroisocyanauric acid, used for disinfectant and bleach.

‍     “We have an environmental contractor and a salvage contractor on site assisting the fire department with the situation,” he said. “The cause of the fire remains undetermined.”

‍     Vancouver fire Assistant Chief Dan Wood said the location of the container — colloquially known as a “can” — initially made it difficult to get to.

‍     “The can was buried,” he said. “It was one can in and two cans back on the corner. It was difficult to access.”

‍     He said he didn’t know yet whether any of the adjacent containers also held the chemical.

‍     Wood said firefighters isolated the burning container as quickly as possible once the fire was reported, building a berm around it to prevent run-off of its contents.

‍     “We’ve got manhole covers blocked and we’ve isolated the drains around the container,” he said.

‍     He added that the fire department was fortunate that there was no rain, which would have made its containment efforts more difficult.

‍     Chief John McKearney said that although firefighters got to the port within four minutes of receiving the alarm, they initially had difficulty locating and isolating the container.

‍     The port had reopened and was operating normally. The Centerm terminal where the fire happened, which is owned by Dubai-based DP World, remained closed, the port said.

‍     DP World said in a news release that its emergency response team was working with authorities to investigate and determine the fire’s cause.