Police technicians have detonated three improvised explosive devices at Toronto's Leslie Street Spit after finding the bombs in the trunk of a car.

Southbound lanes of the Don Valley Parkway and all lanes of the Gardiner Expressway -- both major arteries in and out of the city's downtown core -- were reopened after police shut down traffic to transport the explosives.

At a news conference Friday afternoon, Deputy Police Chief Tony Warr said the three bombs were each about 35 centimetres long.

Police say the three explosives are linked to the arrest of a 37-year-old man taken into custody Thursday night. The man is the subject of an ongoing investigation into letter bombs mailed to two residences in Toronto and one in Guelph.

The bombs were discovered in the trunk of the man's silver sedan, Warr confirmed at an earlier news conference Friday morning.

The car was parked at an Esso gas station near Overlea Boulevard near Thorncliffe Park Drive.

Warr said police believe the three letter bomb incidents and the explosives found in the vehicle, are linked.

The motive behind the letter bombs appears to be personal between the suspect and the recipients, Warr said.

Police have identified the man arrested on Thursday night as Adel Arnaout.

Arnaoult has been charged with:

• Three counts of attempted murder;

• Three counts of intending to cause explosion;

• One count of possessing explosives for unlawful purposes.

Toronto police recently asked the public to closely scrutinize any suspicious packages they received in the mail after two letter bombs were received by city residents.

On Aug. 19, a real estate lawyer living in the city's Sheppard Avenue and Yonge Street area received an envelope that smelled of petroleum. The lawyer alerted police and the package was detonated safely.

About a week earlier, a resident of the city's east end, near Victoria Park Avenue and Lawrence Avenue East, received a bubble-wrapped envelope that also contained a petroleum-like liquid. A male resident was injured when he tried to open the package and it exploded in his hands.

Both packages were 21.6 cm by 27.9 cm and each had properly addressed courier receipts attached. They were also both rigged to explode when opened. The courier company has said it did not send the packages.

A third package was mailed to a residence of Guelph.

With a report from CTV Toronto's Jim Junkin