A senior garda involved in the war on organised crime has said the recent killings in the Hutch-Kinahan feud have been "staggering".
Det Supt Tony Howard, of the Garda Drugs and Organised Crime Bureau (DOCB), said the growing number of killings had raised serious concerns in the force.
He was speaking at a garda press briefing following the seizure of €2m worth of drugs by the DOCB within the space of 72 hours.
"Certainly, when we look at people being murdered in the streets of Dublin as callously as they have been, and the same being repeated in Spain, we are naturally worried," said Det Supt Howard.
He added that gardai are working with their counterparts abroad to tackle serious crime.
"We would liaise with our colleagues, not just in Ireland and England but also in mainland Europe, with Europol and with Interpol," he said.
"We share a lot of intelligence and information and we help each other.
"The level of violence in a short period of time earlier this year was quite staggering and it certainly set alarm bells ringing."
Det Supt Howard the €2m worth of drugs had been seized during operations across the Dublin region as well as in Co Meath and Co Louth.
Raids were carried out by DOCB members, backed up by local garda and members of the Special Crime Task Force, in Finglas and Castleknock, Bellewstown, Co Meath and Dundalk, Co Louth.
Det Supt Howard also said the seizure of a number of high-grade military weapons - including five assault rifles - so far this year is a "worrying trend".