Four suspected Irish Republican Army dissidents were arrested Thursday in connection with a bomb attack that wounded an officer earlier in the week, police said.

The four, arrested in rural County Tyrone, were being questioned at the main police interrogation center west of Belfast in connection with Monday’s attack, authorities said.

A small bomb went off beneath the seat of the police officer’s patrol car as he was driving to work. The officer _ a Catholic _ remained hospitalized Monday with wounds to his legs and back.

Such booby-trap bombs were frequent during the IRA’s failed 1970-97 campaign to oust Northern Ireland from the United Kingdom. Dissidents reject the IRA’s decisions to renounce violence and disarm.