An unlucky incident

Please help me to correct them, thanks!!

1 Peter is a helpful and obedient boy. He always helps (his) mother to do household chores. One sunny morning, Peter ‘s mother brought a washing board / a wash board and a tub of clothes. Peter followed his mother (walking )to the riverside.

2 When / While / As his mother was washing clothes, Peter accidentally slipped and fell into the river. His mother saw him struggling and (going to drown) in the river. His mother was very scared and shouted for help.

3 Luckily, there were some villagers passing by (the river). They heard his mother’s cries and ran towards the (directions of the) river. They dived into the river and tried to pull him back. After half an hour, Peter was saved from drowning. His mother felt grateful to the villagers. / His mother thanked them for their help.