The district's outskirts were also overwhelmed by the run-off, with water levels on Unakul Road reportedly reaching depths of one metre.
The flooding enraged local residents who have complained it is being caused by sluice gates remaining shut to protect areas downstream.
The villagers Thursday blockaded a road in Kabin Buri municipality, calling on authorities to deal with the problem.
They have threatened to dig up a road along the irrigation waterway in tambon Wandan to discharge the floodwater from the area.
The water levels in Kabin Buri municipality continued to rise Thursday as more water kept coming from Sa Kaeo. All municipality roads were flooded and impassable.
In Prachin Buri's Si Maha Phot district, floodwaters rose another 20cm and started to swamp Ban Khok Mai Dang, where flooding had not been seen earlier.
Water management expert Seree Supratid of Rangsit University's College of Engineering said the Prachin Buri flood was the result of poor water management.
The province has flooded every year since 2011.
This year's rainfall was not as heavy as last year, but flood levels are higher and the situation is the worst in 25 years, he said. Local authorities did not open water gates to drain floodwater to farming areas for fear of causing conflict between farmers and other residents, Mr Seree said.
If the sluice gates were not opened, the flood situation would get worse, he said.
Meanwhile, 16 districts in Ubon Ratchathani have been declared flood disaster zones. More than 2,000 houses and 20,000 rai of farmland in 62 tambons have been flooded after days of heavy rain.
In Chaiyaphum, the Chi River Thursday burst its banks, causing damage to three weirs in tambon Thung Thong of Ban Khwao district.
More than 300 houses in tambon Thung Thong municipality were submerged under 1.8m of swirling floodwater.
The run-off also spread to Chatturat district, flooding eight more tambons there.
A 64-year-old local, Noree Chanachai, of tambon Lahan was swept away by floodwaters and was believed to have drowned while fishing late on Wednesday.
In Nakhon Ratchasima's Muang district, the water levels of various waterways also rose. A canal overflowed and flooded Ban Na Tom in tambon Nong Krathum.
Lertviroj Kowattana, director-general of the Irrigation Department, said Thursday flooding in several northeastern provinces, including Prachin Buri, could ease within the next seven days.
Several Central Plains provinces were still struggling with floods Thursday, however. In Phitsanulok, five districts - Muang, Bang Krathum, Wang Thong, Wat Bot, Nakhon Thai - have been declared disaster zones with 1,249 houses and 4,721 rai of paddy fields under water.
The Chao Phraya River rose 10cm in Ayutthaya Thursday, aggravating the flood crisis in Bang Ban district.
Deputy Prime Minister Plodprasop Suraswadi insisted Thursday this year's floods would not be as critical as those of 2011 because there was still 12,300 million cu/m of capacity in reservoirs.