A second suspect has been arrested in connection with an attempted attack on the US embassy in Vienna, Austrian officials have said.
Experts are trying to determine if the devices could have exploded
The man was arrested in Tulln, some 25km (15 miles) west of the capital.
Police said he was suspected of being an accomplice to a Bosnian man arrested on Monday after he tried to take a bag of explosives into the US embassy.
The man attempted to run off after his backpack activated a metal detector. No-one was injured in the incident.
The suspect arrested on Tuesday was also a Bosnian national, police said.
The first of the two suspects in Monday's attack was caught by police at around 1200 (1000 GMT) not far from the US embassy, which is situated on Boltzmanngasse street in Vienna's 9th district.
Doris Edelbacher of Austria's federal counter-terrorism office said explosives found inside his bag resembled grenades, but experts were still trying to determine whether the devices could have been detonated.
"There were a lot of nails in that bag. Had it exploded, it would have had an enormous shrapnel effect," she told the Associated Press.
The backpack also contained a book in which a reference to Islam appeared, she said, but it was too early to say whether the attacker had been motivated by a militant Islamist ideology.
Ms Edelbacher said the suspect spoke broken German and had for now only made "confused statements" whilst being questioned.
Last month, Austrian authorities arrested three people of Arab origin in connection with a video posted online that threatened Austria and Germany with attacks if the two countries did not withdraw their military personnel from Afghanistan.
The arrests came several days after a telephone bomb threat triggered an alert at a US air base at Spangdahlem in Germany.