A member of the emergency services has lost two of his front teeth after he was attacked by a patient he was tending to on a bus.
The 44-year-old paramedic was assaulted on the 41 bus after the passenger - who had appeared to be unconscious - punched him in the face.
The medic was knocked unconscious and needed emergency treatment.
The incident happened in Dublin city centre yesterday morning.
Dublin Fire Brigade (DFB) received a call from Dublin Bus to attend an incident on Abbey Street at 7.40am.
After stirring, the 27-year-old passenger punched the paramedic, dislodging his two front teeth, before getting up and exiting the bus.
He was detained by a nearby security guard as he tried to leave the vehicle, while gardai were called.
Officers from Store Street Garda Station attended the scene on bikes and arrested the attacker.
He was held on suspicion of assault causing harm and was last night being questioned at Store Street.
The paramedic was brought to the Mater Hospital before being transferred to the Dental Hospital.
The attacker is understood to be an Irish national.
The incident has been condemned by the DFB, which said it wished its colleague a speedy recovery.
"Dublin Fire Brigade can confirm that one of its firefighter- paramedics was assaulted in the city centre this morning," a statement said.
"The member of staff was part of an ambulance crew treating a patient at the time.
"Dublin Fire Brigade management and staff condemn incidents of this nature, which are totally unacceptable.
"We will support our colleague and wish him a full and speedy recovery."
The DFB said it would assist gardai in their investigation in any way possible.
Lord Mayor of Dublin Nial Ring called the incident "unacceptable".
Mr Ring said any acts of violence against emergency services personnel could not be tolerated.
He said that for a paramedic to be attacked by someone he was tending to was "reprehensible".
"As you know, firefighters put their lives on the line for us all the time," he said.
"Anyone interfering with a firefighter trying to do their duty is reprehensible. It's unacceptable."
Mr Ring called for gardai to come down as hard as they could on such acts of violence against emergency services personnel, and said he hoped the injured paramedic would make a speedy recovery.