Tempers flared Monday along a barrier protecting the Thai capital from record flooding, with angry residents outside the flood wall overpowering security forces to force open a floodgate that left their homes under water.

The confrontation in the city’s northeastern sector came as Prime Minister Yingluck Shinawatra voiced renewed focus on repairing ruptures in the barriers that are allowing water to seep into central Bangkok — home to hundreds of cultural landmarks, including the Grand Palace and a host of tourist attractions.