Brisbane, Australia (CNN) -- Recovering from flooding in northeastern Australia will be a "reconstruction task of post-war proportions," a top official in Queensland state said Sunday.
"We have massive infrastructure damage that will take months and in some cases years to fully repair," Queensland Premier Anna Bligh told reporters. "We have homes and lives torn apart, in some cases ... by an event of the most traumatic proportions. So we cannot underestimate what is happening."
Police in the flood-ravaged state said Sunday that the death toll from flooding had climbed to 18, and they urged residents to knock on their neighbors' doors as waters recede.
"Many people don't have friends and family to check on them, so it's up to the whole community to do their part and look out for their neighbors," acting Inspector Gareth Bosley said, according to a statement on the Queensland Police website.
Meanwhile, flood warnings were in place Sunday in Victoria state in southeastern Australia as authorities said heavy rains threatened homes there.
Police said 14 people are missing in Queensland, many of them in the Toowoomba and Lockyer Valley areas.
The missing include people who were swept from cars or were in houses that collapsed.
"Credible and reliable information provided to police indicates that these people were caught up in the storm surge that swept the valley, and police hold grave fears for their well-being," Queensland Police Service said in a statement.
Among those who died were Llync-Chiann Clarke, 31, and her two children, ages 5 and 12, who were swept to their deaths as a rescue fire truck became inundated by floodwaters on a local road. Two other people escaped.
Robert John Kelly, 30, was found dead in an upside-down vehicle in a creek, authorities said. The body of Jean Gurr, 88, who was trapped by rising water, was found in her residence.
A teenager who was afraid of water drowned in the Queensland floods after begging rescuers to save his younger brother first.
Jordan Rice, 13, and his mother Donna, 43, were swept away as a wall of water hit the town of Toowoomba last week.
His family has hailed the youngster's selfless actions.
"Jordan can't swim and is terrified of water," his father, John Tyson, told local newspaper The Toowoomba Chronicle. "But when the man went to rescue him, he said, 'save my brother first.'"
Officials warned the cleanup would take months.
More than 20,000 homes were inundated after the normally subdued Brisbane River turned into a raging torrent as weeks of rain pushed it to more than 4 meters (13 feet) at high tide last week. Residents in Brisbane were urged not to enter floodwaters because of the risk of illness after sewage plants along the river were inundated.