A Garda was slashed across the face after he stopped a man suspected of stabbing another man as he sat in a park with his partner and young son.
The officer challenged the suspect in Raheny, north Dublin, yesterday evening after the 33-year-old had been attacked with a broken bottle.
The injured man had been in St Anne's Park with his family, including his four-year-old son, when he was targeted in an unprovoked attack at about 6pm.
His injuries were not serious.
A Garda later challenged a man suspected of the attack in Main Street, Raheny, and was assaulted.
A Garda spokesman said the officer suffered lacerations around an eye but he was released from hospital after treatment.
A man in his 20s was arrested at the scene. He is being detained under Section 4 of the Criminal Justice Act at Raheny Garda Station.
Aodhan O Riordain, Labour TD for Dublin North Central, condemned the attacks.
"There is no doubt that the officer involved in this incident must be commended for his bravery in his attempt to deal with the situation. I wish him a full recovery," he said.