An 89-year-old man has been arrested on suspicion of shooting and wounding several people in attacks on government buildings in Athens.

Hours after the double shooting in the Greek capital, authorities announced a suspect had been detained in the western port city of Patras, reportedly attempting to flee to Italy. His arrest followed a countrywide manhunt.

“He has been detained in custody,” a police source said. “He was armed.”

The attacks unfolded earlier on Tuesday when a gunman walked into a social security office and opened fire with what appeared to be an antiquated shotgun, injuring a female employee in the leg.

That attack was followed by a second assault on an appeals court, where a man entered a chamber while in session and opened fire, lightly wounding four court officials.

The court building was immediately evacuated but not before the gunman had fled the scene.

Greece’s state-run TV channel, ERT, said a relative had been in contact with the broadcaster to say that the suspect had a history of mental illness and had been angered by the rejection of an application for a state pension.

The attacks are particularly shocking to a nation unused to gun violence. Judicial authorities slammed the Greek government for the inadequate security measures that had enabled the gunman to pass unnoticed into a courthouse.

In a statement, the Greek association of judges and prosecutors said the armed attack “demonstrated in the worst possible way the absence of appropriate security measures” in a public building of an EU member state that was used every day.

Highlighting the lax measures, Sotiris Tripolitsiotis, the general secretary of the association of court employees of Athens, claimed X-ray machines acquired to boost security in the courthouse remained “unused” seven years after they were bought because of the lack of properly trained staff.

“No one coming into the courts can really be checked,” he told the Greek daily Kathimerini. The government, he said, had been urged to step up security because increasingly courts were hearing confiscation and debt cases that were prone to make people “angry and violent”.

Greece endured one of Europe’s worst debt crises until near empty state coffers were rebalanced after nearly a decade of tough austerity. Poorer Greeks on wages and pensions that remain lower than other parts of the EU still struggle to make ends meet at a time of rising living costs.